The opinion of the Court was delivered by
COLEMAN, J.In State v. Hightower, 120 N.J. 378, 577 A.2d 99 (1990), this Court affirmed the 1986 capital murder conviction of defendant, Jacinto K. Hightower, but reversed his death sentence and remanded the matter for a new penalty-phase proceeding. At the second penalty trial, defendant was again sentenced to death. Defendant presently appeals that sentence pursuant to Rule 2:2— 1(a)(3). Because of juror misconduct during jury deliberations that exposed the jury to extraneous influences, we reverse and remand for a new penalty trial.
*245I
The facts and procedural history of this case are fully set forth in Hightower. See Hightower I, supra, 120 N.J. at 386-99, 577 A.2d 99. Thus, we limit our recitation to only the facts and history relevant to this appeal.
Shortly after 12 p.m. on July 7, 1985, during the course of a robbery in a Cumberland Farms convenience store, defendant shot the clerk, Cynthia Barlieb, in her chest after she refused to comply with his demands to open the cash register. After falling to the floor as a result of the gun shot wound, Barlieb stood up, cried out and again refused to comply with defendant’s repeated demands to open the cash register. Defendant shot Barlieb again, this time in the neck. While Barlieb laid on the floor, she touched defendant’s leg. Defendant then shot her in the head. At 12:40 p.m. a customer discovered Barlieb’s body in the store’s dairy freezer.
Defendant was indicted for purposeful' murder by his own conduct, contrary to N.J.S.A. 2C:11-3a(1); knowing murder by his own conduct, contrary to N.J.S.A. 2C:11-3a(2); felony murder, contrary to N.J.S.A. 2C:11-3a(3); first-degree robbery, contrary to N.J.S.A. 2C:15-1; second-degree possession of a weapon for an unlawful purpose, contrary to N.J.S.A. 2C:39-4a; and third-degree unlawful possession of a handgun, contrary to N.J.S.A. 2C:39-5b.
In October 1986, the jury found defendant guilty on all counts of the indictment. During the penalty trial, the State asked the jury to consider three aggravating factors: (1) “[t]he murder was outrageously or wantonly vile, horrible or inhuman in that it involved torture, depravity of mind, or an aggravated assault to the victim,” N.J.S.A. 2C:11-3c(4)(c); (2) “[t]he murder was committed for the purpose of escaping detection, apprehension, trial, punishment or confinement for another offense committed by the defendant,” N.J.S.A. 2C:11-3c(4)(f); and (3) “[t]he offense was committed while the defendant was engaged in the commission of, *246or an attempt to commit, or flight after committing or attempting to commit ... robbery,” N.J.S.A. 2C:11-3c(4)(g).
The defense, on the other hand, produced six expert witnesses, and submitted five mitigating factors to the jury: (1) “[t]he defendant was under the influence of extreme mental or emotional disturbance insufficient to constitute a defense to prosecution,” N.J.S.A. 2C:11-3c(5)(a); (2) “[t]he age of the defendant at the time of the murder,” N.J.S.A. 2C:11-3c(5)(c); (3) “[t]he defendant’s capacity to appreciate the wrongfulness of his conduct or to conform his conduct to the requirements of the law was significantly impaired as the result of mental disease or defect or intoxication, but not to a degree sufficient to constitute a defense to prosecution,” N.J.S.A. 2C:11-3e(5)(d); (4) “[t]he defendant has no significant history of prior criminal activity,” N.J.S.A. 2C:11-3e(5)(f); and (5) “[a]ny other factor which is relevant to the defendant’s character or record or to the circumstances of the offense.” N.J.S.A. 2C:11-3c(5)(h).
On November 10, 1986, defendant was sentenced to death after the jury found that the State had proven each of the aggravating factors beyond a reasonable doubt. Although the jury determined that defendant had established two mitigating factors, N.J.S.A. 2C:11-3c(5)(f) and (h), it found that each of the aggravating factors outweighed all of the mitigating factors beyond a reasonable doubt, and that all of the aggravating factors outweighed all of the mitigating factors beyond a reasonable doubt.
On appeal, this Court reversed the death sentence because the Attorney General conceded that the trial court erroneously charged the jury to consider only those mitigating factors found to have been unanimously established. State v. Hightower, supra, 120 N.J. at 386, 577 A.2d 99.
II
Jury selection for the new penalty trial was conducted between September 12 and October 24,1994. Thereafter, a seven-day trial ensued. The State relied on two aggravating factors: murder to *247avoid apprehension, N.J.S.A. 2C:11-3e(4)(f); and murder during a robbery, N.J.S.A. 2C:11-3c(4)(g). Defendant relied on fourteen mitigating factors: (1) defendant’s age at the time of the murder, N.J.S.A. 2C:11-3c(5)(c); (2) defendant had no prior record of criminal convictions, N.J.S.A. 2C:11-3c(5)(f); (3) defendant was never adjudicated a juvenile delinquent, N.J.S.A. 2C:11-3c(5)(h); (4) defendant was sodomized as a young child, ibid.; (5) defendant’s mother was diagnosed as suffering from a severe emotional disorder during his childhood, ibid.; (6) defendant during his formative years frequently assumed responsibility for the care of his younger twin siblings, ibid.; (7) defendant was placed in foster care during his formative years, ibid.; (8) during his formative years, defendant’s mother deserted the family for periods of time, on one occasion during the holiday season, ibid.; (9) defendant was raised in an abusive and dysfunctional environment, ibid.; (10) the imposition of the death penalty would entail excessive hardship on members of defendant’s family, ibid.; (11) defendant was engaged in productive employment while in state prison, ibid.; (12) defendant did not know the identity of his natural father, ibid.; (13) defendant witnessed the abuse of his siblings during his formative years, ibid.; and (14) any other mitigating factor that the jury found to exist. Ibid.
The only testimony presented by the State was that of Christopher Forston who had also testified at the guilt trial. Forston testified about a conversation that he had with defendant after the Cumberland Farms murder in which defendant voluntarily told Forston how he had committed the crime. Forston testified that defendant told him “he had killed a woman in a store because she wouldn’t cooperate with him.” According to Forston, defendant had recounted the crime as follows. Defendant entered the Cumberland Farms carrying a tote bag and waited for the customers to leave. He then picked up a box of Pampers, set it on the counter, walked to the door, turned the “open” sign to “closed,” returned to the counter and asked the clerk for a pack of cigarettes. As the clerk turned her back and reached for the cigarettes, defendant pulled a gun out of his tote bag and demand*248ed the clerk to open the cash register. Forston further testified that defendant stated that “the ‘old bitch’ would not cooperate [so he] shot her one time in the chest.”
Additionally, Forston testified that defendant told him that after the first shot, the clerk fell to the floor but got back up hollering and refused defendant’s second request to open the register. Defendant then shot her in the neck. The woman fell to the floor again. Defendant jumped over the counter and began to bang on the cash register because he did not know how to open it. When he felt the clerk grab his leg, he shot her in the head and left the store.
At the conclusion of Forston’s testimony, defense counsel moved to dismiss the aggravating factor, murder to avoid apprehension, N.J.S.A. 2C:11-3c(4)(f). The defense argued that the State had not produced evidence, either direct or circumstantial, from which the jury could rationally conclude beyond a reasonable doubt that defendant killed Barlieb to avoid apprehension. Rather, the defense insisted that Forstón’s testimony was direct evidence that defendant killed Barlieb solely because she refused to cooperate. The trial court denied the motion, reasoning that a factual issue was presented and required a determination by the jury. The case was submitted to the jury with a special verdict sheet.
The jury commenced its deliberations on October 31, 1994, at 3:15 p.m. After deliberating for approximately one hour, the jury recessed for the day. The trial court collected from the foreperson the verdict sheet on which the jury had made some notations, as well as other notes, and sealed them in an envelope. The following morning, the jury reconvened at 9:15 a.m. to continue its deliberations. After approximately six and one-half hours of deliberating, over a two-day period, the jury submitted the following note to the court:
[I]t has come to our attention that one of the jurors has information and knowledge about this case beyond the scope of the evidence given in Court. We ask your direction in regard to this matter.
*249The court responded by instructing the jurors to temporarily suspend deliberations and not to discuss the case or the subject of the note. The trial court then interviewed each juror individually in chambers and in the presence of counsel. During those interviews, the judge asked each juror not to reveal his or her position to the court, or to any other juror, with respect to the point at which each juror was in the deliberations or any position taken.
Notwithstanding the judge’s instructions, the jury foreperson disclosed during the interview that Juror Number 7 had informed the jury that he had heard, outside of the courtroom, that the victim had three children. Describing the context in which Juror Number 7 made the statement, the foreperson explained:
There was a fairly intense debate going on at that point in time where [Juror Number 7] was taking a different position than some of the other people, and there was a fair amount of frustration from some other people about the position he was taking, and essentially he was ... getting backed into a corner ... and he was almost lashing out.
The foreperson’s account of Juror Number 7’s statement and the circumstances surrounding it were confirmed by several other jurors. Indeed, Juror Number 7 admitted in his interview making that statement about the victim having children. He stated that he had overheard that statement while he was shopping in a store earlier in the week. He pointed out, however, that he did not partake in the discussion.
At the conclusion of the interviews, despite the trial court’s efforts to avoid learning the jurors’ positions on the merits of the ease, the position of Juror Number 7 had been disclosed by both Juror Number 7, and the foreperson. For example, at one point during the his interview, the foreperson stated that Juror Number 7 “was taking a different position than others in the room.” Additionally, in responding to a question from the trial court, Juror Number 7 explained:
I told them I thought that he should get 30 years imprisonment instead of the death sentence because it seems by his time in prison he could be a productive citizen when he come out. Now, majority of them jumped me for that____ Well, they said, you must have heard something we didn’t hear, and I says, all I *250overheard — I didn’t discuss this with no one — was that the lady had three children____
Interviews with other jurors also revealed that Juror Number 7 may have engaged in other misconduct, namely, dishonesty in responding to questionnaires completed during the jury selection process. The specific act of dishonesty alleged was that the juror failed to disclose that he opposed the death penalty and that he had visited prisons in the past.
Finally, during the interviews several jurors told the trial court that at the time Juror Number 7 informed the jury that the victim had children, the jury had reached a rather advanced • stage of deliberations. One juror indicated that he had already made up his mind when he learned of the information; another revealed that the jury had already taken a straw vote; and the foreperson stated that the jury was at a “fairly late point” in its deliberations. In addition, the verdict sheet indicated that the jury had made tentative determinations with respect to the existence of both aggravating factors and all mitigating factors. The only section of the verdict sheet left unmarked was that reserved for the jury’s ultimate conclusion with respect to the sentence.
Having all this information, the trial court then heard arguments from the State and defense counsel, outside the presence of the jury, regarding how to resolve the jury crisis. The State recommended that the court remove Juror Number 7 from the jury, insert an alternate, and instruct the jury to begin deliberations anew. Defense counsel, on the other hand, insisted that the appropriate remedy was a mistrial, or in the alternative, that deliberations should continue with Juror Number 7 on the jury because Rule 1:8 — 2(d) did not authorize removal for the type of misconduct involved.
Agreeing with the State, the trial court rejected defense counsel’s request and ordered that Juror Number 7 be removed from the jury and replaced with an alternate. In denying the application for a mistrial, the court reasoned that it had no conclusive information concerning the positions of any of the jurors, except *251Juror Number 7, on the merits of the case. The court further explained that six hours of deliberations in the penalty phase of a capital case was not a very long time. The court then declared that its main reason for removing Juror Number 7 from the jury was that the juror had revealed information learned outside of the courtroom to the jury instead of to the court as instructed. The trial court expressed concern that the juror had the potential to repeat the misconduct. The court further considered the necessity to protect the integrity of the process that had been threatened by the conduct of Juror Number 7.
After the judge’s ruling, an alternate juror was selected and the entire jury was instructed to continue its deliberations. The judge cautioned the newly-constituted jury that it was to “totally disregard” the outside information revealed by removed-Juror Number 7, and begin its deliberations anew. The court provided the new jury with a blank verdict sheet, retaining the former verdict sheet and notes in a sealed envelope. The reconstituted jury recommenced deliberations on November 2, 1994, at 11:03 a.m. Four and one-half hours later, the jury returned a verdict of death.
A poll of the jury confirmed that it had unanimously concluded, beyond a reasonable doubt, that both aggravating factors existed, namely, murder to avoid apprehension, N.J.S.A 2C:11-3c(4)(f), and murder committed during the commission of another crime, N.J.S.A. 2C:11-3c(4)(g). The poll further confirmed that the jury was unanimously satisfied that any and all of the aggravating factors outweighed the ten mitigating factors found to exist. The accepted mitigating factors were: (1) defendant’s age at the time of the murder; (2) defendant had no prior record of criminal convictions; (3) defendant was never adjudicated a juvenile delinquent; (4) defendant was sodomized as a young child; (5) defendant’s mother was diagnosed as suffering from a severe emotional disorder during his childhood; (6) during his formative years, defendant had frequently assumed responsibility for the care of his younger twin siblings; (7) during his formative years, defendant was placed in foster care; (8) during his formative years, *252defendant’s mother would desert the family for periods of time, on one occasion during the holiday season; (9) defendant was raised in an abusive and dysfunctional environment; and (10) the imposition of the death penalty would entail excessive hardship on members of defendant’s family. Accordingly, defendant was sentenced to death.
After the verdict was received, defense counsel requested that the court question the foreperson to determine the stage that the jury had reached in its deliberations when the new juror was substituted. Defense counsel also requested that the court seal and preserve the original jury’s verdict sheet and notes for use on appeal. The trial court denied the first, but granted the second motion. We unsealed the verdict sheet pursuant to an order dated June 7, 1995. The sheet revealed that the first jury had tentatively found both aggravating factors and had made tentative findings on all of the fourteen mitigating factors. The sheet did not indicate, however, whether the jury’s vote was final, whether the aggravating factors outweighed the mitigating or whether the jury would impose the death penalty or life imprisonment.
Ill
Preliminarily, we reject defendant’s claim that the New Jersey Death Penalty Act (Act) violates the Eighth Amendment to the United States Constitution. In State v. Biegenwald, 126 N.J. 1, 594 A.2d 172 (1991), this Court upheld the constitutionality of the Act in the face of equivalent challenges. Id. at 16, 594 A.2d 172; accord State v. Harris, 141 N.J. 525, 574, 662 A.2d 333 (1995); State v. Moore, 122 N.J. 420, 486, 585 A.2d 864 (1991); State v. Hunt, 115 N.J. 330, 373, 558 A.2d 1259 (1989); State v. Koedatich, 112 N.J. 225, 249, 548 A.2d 939 (1988), cert. denied, 488 U.S. 1017, 109 S.Ct. 813, 102 L. Ed.2d 803 (1989); and State v. Ramseur, 106 N.J. 123, 185-90, 524 A.2d 188 (1987). In addition, the constitutionality of the aggravating factor, N.J.S.A. 2C:11-3e(4)(c), has been upheld. State v. Ramseur, supra, 106 N.J. at 188-89 n. 21, 524 A.2d 188.
*253IV
Defendant argues that Rule l:8-2(d) did not permit the trial court to remove Juror Number 7. He contends that even if that juror’s disclosure of the out-of-court information rendered him “unable to function,” his inability to function was not due to him personally; rather it was due to his interaction with other jurors or at least a combination thereof.
Rule 1:8 — 2(d) governs the removal and substitution of deliberating jurors. The Act complements the court rule by providing that “[njothing in [the] statute shall be construed to prevent the participation of an alternate juror in the sentencing proceeding if one of the jurors who rendered the guilty verdict becomes ill or is otherwise unable to proceed before or during the sentencing proceeding.” N.J.S.A. 2C:ll-3c(l). The court rule for removal provides in pertinent part:
If the alternate jurors are not discharged and if at any time after submission of the case to the jury, a juror dies or is discharged by the court because of illness or other inability to continue, the court may direct the clerk to draw the name of an alternate juror to take the place of the juror who is deceased or discharged.
[R. 1:8—2(d).]
Despite the rule’s broad language, trial courts do not have unbridled discretion to reconstitute deliberating juries in the face of a jury crisis. On the contrary, the removal rule may be used only in limited circumstances. Clearly, frequent reconstitution of deliberating juries could destroy the integrity and the mutuality of deliberations, thereby depriving defendants of the right to a fair trial by an impartial jury. The “mutuality of deliberations” is at the core of jury deliberations. It entails the joint or collective exchange of ideas among individual jurors that remains intact until a final determination is reached. State v. Corsaro, 107 N.J. 339, 349, 526 A.2d 1046 (1987). Mutuality may be destroyed if juror substitution is not made in accordance with the limited scope of the rule for removal. Ibid.; R. 1:8-2(d). Therefore, any conduct that could upset the process of jury deliberations, even judicial conduct such as juror substitution, must be carefully scrutinized.
*254Because juror substitution poses a clear potential for prejudicing the integrity of the jury’s deliberative process, it should be invoked only as a last resort to avoid the deplorable waste of time, effort, money, and judicial resources inherent in a mistrial. State v. Lipsky, 164 N.J.Super. 39, 43, 395 A.2d 555 (App.Div.1978).
The rule permits substitution of an alternate when the deliberating juror dies, becomes ill “or is otherwise unable to continue.” These are, of course, precisely the circumstances mandating substitution of a juror during the trial itself. Because they relate exclusively to the personal situation of the juror him [or her] self and not to his [or her] interaction with the other jurors or with the case itself, they are ordinarily not circumstances having the capacity to affect the substance or the course of the deliberations. Hence the continuation of the trial with a substituted alternate is in these circumstances no way violative of defendant’s right to trial by a fair and impartial jury. In this respect the “unable to continue” standard is much narrower than the concept of good cause requiring the discharge of prospective jurors before trial commences. “Good cause” in that context includes potential juror bias which would irremediably taint the entire jury, particularly in its deliberative process. Removal of such a juror after trial has commenced and even more particularly after deliberations have commenced cannot ordinarily repair the harm already done or presumed to have been done. Juror bias discovered during deliberations is clearly, therefore, not a circumstance susceptible to the discharge and substitution technique of the rule. Declaration of a mistrial would be the only available alternative.
[State v. Trent, 157 N.J.Super. 231, 239, 384 A.2d 888 (App.Div.1978), rev’d on other grounds, 79 N.J. 251, 398 A.2d 1271 (1979).]
Although the death and illness standards are clear and narrow, the “inability-to-continue” standard, at first glance, appears vague and rather broad. That standard, however, must be narrowly construed and sparingly applied. State v. Valenzuela, 136 N.J. 458, 468, 643 A.2d 582 (1994); State v. Trent, supra, 157 N.J.Super. at 240, 384 A.2d 888.
Some of the questions concerning the narrow scope of the inability-to-continue standard were clarified in Valenzuela, in which the Court stated that to remove under the standard
the record [must] adequately establish ] that the juror suffers from an inability to function that is personal and unrelated to the juror’s interaction with the other jury members. If a court suspects that the problems with the juror are due to interactions with other jurors, the court should instruct the jury to resume deliberations.
[State v. Valenzuela, supra, 136 N.J. at 472-73, 643 A.2d 582.]
*255Thus, the inability-to-continue standard may not be invoked to remove a deliberating juror when the record merely reveals that the juror has a position that is different from that of other jurors. Id. at 468-69, 648 A.2d 582. Nor may the standard be employed to remove a deliberating juror where the record reveals that the juror’s problems are related to both personal circumstances and factors arising from the juror’s interactions with other jurors. Id. at 473, 643 A.2d 582. In other words, the reason must be exclusively personal.
Conversely, the standard may be invoked to remove a juror when the record reveals that the juror’s emotional condition renders him or her unable to render a fair verdict. E.g., State v. Miller, 76 N.J. 392, 406-07, 388 A.2d 218 (1978) (holding that removal of juror was warranted when juror’s nervous and emotional condition renders him or her unable to render fair verdict); State v. Trent, supra, 157 N.J.Super. at 240, 384 A.2d 888 (finding that removal of juror was warranted when juror suffered from severe emotional and physical distress that made it impossible for juror to continue).
Under the facts and circumstances presented in this case, we hold that the trial court improperly expanded the scope of Rule l:8-2(d)’s inability-to-continue standard when it removed Juror Number 7 from the deliberating jury. Although the juror did not follow the trial court’s instructions to report to the court any information he overheard outside of the courtroom, and violated his oath by informing other jurors that the victim had children, that misconduct does not fall within the scope of Rule 1:8 — 2(d)’s inability-to-continue standard. That standard requires exclusively personal circumstances to justify removal of a deliberating juror. Juror Number 7 did not satisfy that standard because his misconduct was related to the case and to his interactions with the other jurors. Although it is not inconceivable that there might be some circumstances in which juror misconduct during jury deliberations might permit substitution of the offending juror, under the facts of this case the only option available is the “[declaration of a *256mistrial.” State v. Trent, supra, 157 N.J.Super. at 239, 384 A.2d 888. See infra pp. 264-67, 680 A.2d at 661-63.
We note that the Appellate Division recently revisited the issue of juror substitution under the inability-to-continue standard. In State v. Holloway, 288 N.J.Super. 390, 402-03, 672 A.2d 734 (App.Div.1996), there was no objection to juror substitution because of juror misconduct that occurred after extensive deliberations. The lack of objection and the court’s finding that the misconduct did not taint the remaining jurors distinguish Holloway, however, from our analysis in the present case. See id. at 404-05, 672 A.2d 734. In State v. Singleton, 290 N.J.Super. 336, 675 A.2d 1143 (App.Div.1996), a deliberating juror was excused under the inability-to-continue standard because the juror’s religious views, among other things, interfered with his ability to reach a verdict. Id. at 345-46, 675 A.2d 1143. The Appellate Division found that the juror was improperly removed because of her interactions with other jurors. Id. at 349-50, 675 A.2d 1143. Singleton is consistent with Valenzuela.
V
Defendant claims that because an alternate juror was improperly substituted for Juror Number 7, he was deprived of a non-unanimous verdict notwithstanding that juror’s misconduct.
A non-unanimous verdict in the penalty phase of a capital case is a final verdict of life imprisonment without any further exposure to a death sentence. N.J.S.A. 2C:11-3c(3)(c); State v. DiFrisco, 137 N.J. 434, 483-84, 645 A.2d 734 (1994), cert. denied, _ U.S. _, 116 S.Ct. 949, 133 L. Ed.2d 873 (1996); State v. Hunt, supra, 115 N.J. at 378, 380, 558 A.2d 1259; State v. Ramseur, supra, 106 N.J. at 301, 524 A.2d 188.
The cases relied on by defendant to support his assertion that he was deprived of the opportunity of a non-unanimous verdict fall into two categories. One group is based on the assumption that the jury was deadlocked. The other group focuses on whether the *257jury had advanced too far in its deliberations to permit substitution of a juror. Neither group, however, discusses the appropriateness of declaring a mistrial when a juror’s substitution and juror misconduct prevent the original jury from deliberating until reaching a final verdict.
-A-
There are three so-called jury-deadlock cases. In DiFrisco, after the jury had deliberated in a penalty trial for approximately four hours, it sent a note to the court advising that it had reached a verdict. State v. DiFrisco, supra, 137 N.J. at 481, 645 A.2d 734. As the court was about to receive the verdict, the trial court asked the foreperson whether the verdicts were unanimous. Ibid. When the foreperson answered no, and another juror indicated that the jury had not unanimously found the existence of an aggravating factor, the jury requested that it return to the jury room. Id. at 481-82, 645 A.2d 734. The court ordered the jury to resume its deliberations. Id. at 482, 645 A.2d 734. After further deliberations, the jury imposed the death penalty. Id. at 483, 645 A.2d 734.
This Court rejected an argument that defendant was deprived of a non-unanimous verdict. The Court concluded that despite the jury’s note and its report to the trial court that its verdict was not unanimous, requiring the jury to deliberate further was proper because the jury was not deadlocked. Id. at 485, 645 A.2d 734.
In Hunt, the jury sent a note to the trial court stating that it could not reach a unanimous decision on whether a mitigating factor outweighed an aggravating factor. State v. Hunt, supra, 115 N.J. at 378, 558 A.2d 1259. This Court held that because the trial court failed to inquire of the jury whether its note “stated its verdict or whether the jury wanted more time to deliberate” before requiring further deliberations, and because the jury was not reminded that a non-unanimous verdict was acceptable, defendant was deprived of a realistic possibility that the death sentence would not have been imposed. Id. at 378-79, 558 A.2d 1259. This *258Court therefore barred imposition of the death penalty. Id. at 379, 558 A.2d 1259.
In Ramseur, after the jury had deliberated in the penalty phase for four and one-third hours, the court received a note from the jurors stating, “ ‘Jury unable to reach a unanimous decision. Suggestions please.’ ” State v. Ramseur, supra, 106 N.J. at 301, 524 A.2d 188. Over defense counsel’s objection, the court gave an “Men charge,” as modified by State v. Czachor, 82 N.J. 392, 401-02, 413 A.2d 593 (1980) (reminding jurors of their duty to consult with one another in reaching a unanimous verdict and urging dissenting jurors not to compromise for the purpose of achieving unanimity), and required further deliberations. After being instructed to attempt to reach unanimity two additional times, the jury imposed the death sentence. State v. Ramseur, supra, 106 N.J. at 302, 524 A.2d 188. This Court held that the trial court did not abuse its discretion in failing to declare that the jury was deadlocked when the note was submitted to the court. Id. at 302-04, 524 A.2d 188. Nevertheless, the supplemental charges were found to be coercive because the trial court did not reinform the jury of the consequences of a non-unanimous verdict. Id. at 305, 524 A.2d 188.
Accordingly, under Ramseur, if a jury reports to the court that it is unable to reach a unanimous verdict after about four hours of deliberations, the court is not obligated to declare the jury deadlocked. A trial court is permitted to require a jury to deliberate for a reasonable length of time before declaring a deadlock. Id. at 302-03, 524 A.2d 188; State v. Czachor, supra, 82 N.J. at 407, 413 A.2d 593. What constitutes a reasonable amount of time is influenced by the length of the trial and the complexity of the penalty issues. State v. Ramseur, supra, 106 N.J. at 303, 524 A.2d 188.
The penalty trial in the present case involved the difficult determination of whether the killing during the course of a robbery was to avoid detection or apprehension, N.J.S.A. 2C:11-3c(4)(f), as well as the existence of the 3c(4)(g) murder-during-a-*259robbery aggravating factor and five mitigating factors. “In addition, the jury had to assess the defendant’s mental state and decide whether mitigating factors outweighed aggravating factors.” State v. Ramseur, supra, 106 N.J. at 303, 524 A.2d 188.
When the juror misconduct occurred in the present case, the jury had deliberated no more than six and one-half hours. Although Juror Number 7 apparently wished to impose a life sentence, there is no reasonable basis to assume that the power of persuasive argument would not have ultimately resulted in an uncoerced unanimous verdict for the death sentence. In DiFrisco, Hunt, and Ramseur, the question of whether the jury was deadlocked was precipitated by a note from the jury or a comment by the foreperson to the trial court. In the present case, however, there was no communication from the jury to the court that remotely suggested deadlock. Rather, it was the unsolicited remarks of jurors concerning the misconduct of Juror Number 7 that ignited the issue. Prior to that misconduct, the jury was continuing its deliberations without any suggestion that it had reached a genuine stalemate. Neither a genuine stalemate nor a jury’s verdict is final until announced in open court. Further, when a verdict is reached, it is not final until confirmed by a polling of the jury unless waived. State v. Shomo, 129 N.J. 248, 259, 609 A.2d 394 (1992); 4 Charles E. Torcía, Wharton’s Criminal Procedure § 578 (12th ed. 1976).
A defendant is entitled to a non-unanimous verdict only when the jury is deadlocked after deliberating a reasonable time. Although in the present case the jurors had taken a straw vote and voted on the aggravating and mitigating factors before learning that the victim had children, there is nothing in the record to suggest that the jury would have been unable to reach a unanimous verdict concerning defendant’s sentence. Indeed, the record establishes that the jury was in the midst of deliberations when Juror Number 7 engaged in misconduct involving the other jurors. As one juror noted, an “intense debate” was ongoing when Juror Number 7 revealed the extraneous information. Additionally, the *260verdict sheet that was removed from the sealed envelope confirms that no final vote had been taken and no verdict had been reached.
Furthermore, it is not uncommon for jurors to take several votes during the deliberative process, particularly an initial vote to determine each juror’s position at the outset. See State v. Levitt, 36 N.J. 266, 269, 176 A.2d 465 (1961) (noting that jury took three votes before reaching its ultimate determination, with first vote taken one-half hour after jury began deliberating). Additionally, no litmus test can be devised for determining what is a reasonable time for deliberating. Lengthy deliberations are not uncommon during the penalty phase of a capital case. This Court has acknowledged that because the issues before the jury are so complex, deliberations of more than ten hours may be inadequate to reach a final conclusion on the appropriate sentence. State v. Ramseur, supra, 106 N.J. at 303, 524 A.,2d 188.
We conclude, as did the Court in DiFrisco and Ramseur, that defendant was not deprived of a non-unanimous verdict because the jury had not reached a final verdict and was not deadlocked before the juror misconduct occurred.
-B-
Very few cases have addressed the issue whether a jury has deliberated too far to permit replacement of a deliberating juror with an alternate juror.
Since the 1972 amendment to Rule 1:8 — 2(d), juror substitution during deliberations has been permitted to prevent the necessity of a mistrial, particularly in protracted trials, because of the death, illness or other inability of a juror to continue deliberations until a verdict is reached. Sub-Committee on Criminal Jury Deliberations of the Supreme Court Committee, 95 N.J.L.J. 341, 355 (1972).
Rule l:8-2(d) provides that when good cause is shown, an alternate juror may be substituted for a regular juror after deliberations have begun. Although the rule does not offend our *261state constitutional guaranty of trial by jury, State v. Miller, 76 N.J. 392, 406, 388 A.2d 218 (1978), it should be used sparingly, only within the strict letter of the rule, and as a last resort to avoid the waste of time that would otherwise ensue. State v. Valenzuela, supra, 136 N.J. at 468, 643 A.2d 582; State v. Trent, supra, 157 N.J.Super. at 240, 384 A.2d 888.
In Valenzuela, within two hours after the jury commenced its deliberations, the court dismissed a juror because the juror was unable to deliberate in a coherent manner, and substituted an alternate. State v. Valenzuela, supra, 136 N.J. at 466, 643 A.2d 582. The reconstituted jury was instructed to “begin ... work anew.” Ibid. Although the Court held that the juror substitution was improper because it was based on the excused juror’s interactions with other jurors, id. at 472, 643 A.2d 582, it declined to discuss whether the jury deliberations had advanced too far to permit a substitution. Id. at 473, 643 A.2d 582.
In State v. Moore, 113 N.J. 239, 550 A.2d 117 (1988), the Court held that if an alternate is substituted at the beginning of the penalty phase of a death penalty trial, then guilt need not be deliberated anew. Id. at 306-07, 550 A.2d 117. The Court grounded its holding in the Legislature’s intent to allow for bifurcated guilt and penalty trials where necessary. Id. at 306, 550 A.2d 117.
Corsaro, deals with whether a jury that has returned guilty verdicts against the defendants on some of the counts in an indictment may be reconstituted to consider other charges when one of the deliberating jurors returned to the courtroom intoxicated and more than one hour late. State v. Corsaro, supra, 107 N.J. at 341-42, 526 A.2d 1046. That juror was dismissed and replaced with an alternate; the newly constituted-jury was instructed “to begin your deliberations anew with respect to the open charges that you are considering.” Id. at 344, 526 A.2d 1046. Guilty verdicts were returned on all the remaining charges. Id. at 345, 526 A.2d 1046. The defendants sought new trials on the grounds that a mistrial should have been granted when the intoxicated *262juror was excused. Ibid. The trial court denied the motions and the Appellate Division affirmed. Ibid. This Court reversed, finding that substitution of a juror during the jury’s deliberations after it had returned partial verdicts was improper because the deliberative process had advanced “to such a degree that it [was] strongly inferable that the jury [had] made actual fact-findings or reached determinations of guilt or innocence ... [and] the new juror [was] likely ... confronted with closed or closing minds.” Id. at 352, 526 A.2d 1046. The appropriate remedy was to wait until the original juror was able to continue or declare a mistrial on the remaining charges. Id. at 354, 526 A.2d 1046.
In State v. Trent, 79 N.J. 251, 398 A.2d 1271 (1979), after the jury had deliberated approximately six and one-half hours, one of the jurors was replaced due to illness. Id. at 253, 398 A.2d 1271. The alternate juror was also replaced almost immediately. Id. at 254, 398 A.2d 1271. The jury was not instructed after either substitution to begin the deliberations anew. Id. at 253-54, 398 A.2d 1271. The Court reversed the conviction upon finding that the trial court had erred in failing to instruct the reconstituted juries to commence deliberations anew. Id. at 256-57, 398 A.2d 1271. Trent, however, did not address whether the jury’s deliberations had advanced too far.
In Miller, after the jury had deliberated for approximately one and one-quarter hours, one of the jurors asked to be dismissed because he was too nervous and his nervousness affected his judgment. State v. Miller, supra, 76 N.J. at 401, 388 A.2d 218. Defendant’s request for a mistrial was denied and one alternate juror was substituted. Id. at 401-02, 388 A.2d 218. Like Trent, the Court did not discuss whether the jury’s deliberations had advanced too far.
From the few cases that have discussed whether the jury had deliberated too far to permit substitution pursuant to Rule l:8-2(d), the conclusion to be drawn is that the only other viable option to juror substitution is a mistrial. Even if the remaining eleven jurors were not tainted by the misconduct of Juror Number *2637, a jury of eleven was not permitted in this case. The parties may not stipulate that the jury may consist of fewer than twelve jurors in a capital case. R. l:8-2(a). Because there can be no waiver of a properly constituted jury in a capital ease, any verdict rendered by an improperly constituted jury would be a nullity.
VI
Defendant argues further that although removal of Juror Number 7 was not an available option under Rule l:8-2(d), the trial court should have granted his mistrial application because the jury was exposed to prejudicial out-of-court information about the victim having children.
This Court has consistently held that the essence of a fair trial requires the securing and preservation of an impartial jury, neither tainted by prejudice nor exposed to extraneous influences, even those judicial in nature. State v. Bey I, 112 N.J. 45, 75, 548 A.2d 846 (1988); State v. Corsaro, supra, 107 N.J. at 346-47, 526 A.2d 1046. The United States Supreme Court requires that a jury’s verdict be based on evidence received in open court, not from outside sources. Sheppard v. Maxwell, 384 U.S. 333, 351, 86 S.Ct. 1507, 1516, 16 L. Ed.2d 600, 613 (1966). Trial courts have been required to protect jurors and their deliberations from outside influences that threaten to taint the verdict. State v. Bey I, supra, 112 N.J. at 75-76, 548 A.2d 846. The need to protect the integrity of the deliberative process in a capital ease was summarized in Bey I:
We have explained that “the securing and preservation of an impartial jury goes to the very essence of a fair trial____ [This right] is of exceptional significance____ [T]riers of fact must be as nearly impartial ‘as the lot of humanity will admit.’ ”
Of particular significance here is that aspect of impartiality mandating “that the jury’s verdict be based on evidence received in open court, not from outside sources.” As expressed by Justice Holmes, “[t]he theory of our system is that the conclusions to be reached in a case will be induced only by evidence and argument in open court, and not by any outside influence, whether of private talk or public print.” We recently noted the long-standing nature of this Court’s commitment to the “[preservation of the jury’s independence from extraneous — even judicial— influences.” The Court has consistently required trial courts to protect both jurors *264and their deliberations from illegitimate influences that threaten to taint the verdict.
[Id. at 75, 548 A.2d 846 (alterations in original) (citations omitted).]
When a jury is exposed to extraneous information after deliberations have begun, a mistrial will almost always be required. State v. Kociolek, 20 N.J. 92, 96-97, 118 A.2d 812 (1955). In Kociolek, a jury convicted the defendant of murder and sentenced him to death after it learned during deliberations, from some jury members, that defendant had been indicted on charges of assault and battery in an unrelated matter. Id. at 94, 118 A.2d 812. The trial court attempted to shield the jury from the information concerning the unrelated indictment by instructing the jury to render a verdict based only upon evidence presented inside the courtroom. Id. at 95-96, 118 A.2d 812. Reversing the trial court’s decision to deny the defendant’s motion for a new trial, Justice Brennan, writing for this Court, stated:
[T]he intrusion of the [unrelated indictments] into the jurors’ deliberations, standing alone, introduced illegal and extraneous evidence fraught with peril for the defendant, an action the more grievous because taken in disregard, actually in defiance, of the explicit instructions of the trial judge. Since the law would have allowed a new trial if such extraneous prejudicial matter was erroneously admitted in evidence at the trial, it cannot tolerate the defeat of justice which would result from the indefensible exclusion of the juror’s testimony as to the incident, where the matter came into the jurors’ deliberations despite the commendable effort of court and counsel to prevent the mishap, and the jurors considered it, in violation of the court’s instructions and of their oaths.
[Id. at 103-04, 118 A.2d 812.]
In this case defendant contends that even if the jury was properly reconstituted, a mistrial was nonetheless required because the jurors were exposed to prejudicial victim impact evidence, to wit, that the victim had three children. The revelation of that information, defendant insists, inevitably affected the eleven jurors who had been in favor of a death sentence before learning of the evidence, influenced them to adhere to their views and return a death sentence after learning of the evidence.
Mowing victim impact information to be placed before the jury without proper limiting instructions has the clear capacity *265to taint the integrity of the jury’s decision on whether to impose death. “The determination of a life or death sentence in a capital case is an extraordinarily delicate and sensitive judgment.” State v. Hightower, supra, 120 N.J. at 439, 577 A.2d 99 (Handler, J., concurring in part and dissenting in part). The integrity of jury deliberations is a crucial aspect of a criminal prosecution. State v. Corsaro, supra, 107 N.J. at 346, 526 A.2d 1046. The deliberative process of a jury “must be insulated from influences that could warp or undermine the jury’s ... ultimate determination.” Ibid.
Juror misconduct that causes a substantial likelihood that one or more jurors were impermissibly influenced is enough to undermine the integrity of a death penalty trial without consideration of actual prejudice. That is so because each juror’s vote is decisive, given that each juror must individually determine both the existence of mitigating factors and whether the aggravating factors outweigh the mitigating ones. State v. Bey II, 112 N.J. 123, 161, 548 A.2d 887 (1988) (citing Mills v. Maryland, 486 U.S. 367, 374-77, 108 S.Ct. 1860, 1865-66, 100 L. Ed.2d 384, 393-95 (1988).
The impact that improperly introduced victim impact evidence has on a jury is difficult to gauge. We observe that the trial court’s questions were not framed to detect whether the jurors were influenced by the extraneous information. For example, the trial, court asked one juror if he would be able to continue to decide the case “according to [his] best judgment.” The court asked another juror “with [Juror Number 7] having said that, does that create any problem with you about going ahead and continuing to decide this case or continuing to get to wherever point you all can get?” If one or more of the jurors were already leaning in the direction of a death sentence and were further convinced by Juror Number 7’s comment, then those jurors could have honestly answered the questions without ever indicating any effect that Juror Number 7’s misconduct had on their judgment.
The potential for prejudice stemming from the kind of victim impact evidence Juror Number 7 introduced into the case was *266obvious to both the trial court and counsel. The trial court took extreme precautions to shield the jury from exposure to information about the victim having children, recognizing that such information had a high probability to prejudice the jury against defendant. For example, all prospective jurors who had information from the media or elsewhere concerning the victim’s children were excluded for cause during jury selection. The State, defense counsel, and witnesses were instructed to avoid making any reference to the victim’s children during the trial. In addition, the victim’s ten-year old niece was instructed to sit away from adult members of the victim’s family in the courtroom.
Even if the victim impact information that was improperly placed before the jury could be properly introduced in evidence pursuant to the recently enacted statute, codified at N.J.S.A. 2C:22-3c(6) (see State v. Muhammed, 145 N.J. 23, 678 A.2d 164 (1996) discussing constitutionality of that statute), placing the victim impact information before the jury in this case cannot be regarded as harmless error. That statute and our Rules of Evidence contemplate that the trial court will give special instructions to the jury limiting its use of that evidence. N.J.R.E. 105. Here, the jury was never told how to use the information about the victim’s children. Instead, it was told to disregard it, an instruction the jury could not conceivably carry out.
Thus, the jury’s exposure to the victim impact evidence in the present ease could have, in all likelihood, affected the result. Because the stakes are so high in a death penalty trial, where serious juror misconduct occurs, prejudice will be presumed. Accordingly, we hold that the introduction of victim impact information into the jury’s deliberation in the present case had the clear capacity to prejudice defendant. We find that the trial court abused its discretion in denying defendant’s application for a mistrial.
The standard governing the grant of a new trial is the same for a mistrial. Any juror misconduct or improper intrusion into the deliberations of a jury that “could have a tendency to *267influence the jury in arriving at its verdict in a manner inconsistent with the legal proofs and the court’s charge” is a ground for a mistrial. Panko v. Flintkote Co., 7 N.J. 55, 61, 80 A.2d 302 (1951). A jury’s verdict must be “based solely on legal evidence ... and entirely free from the taint of extraneous considerations and influences.” Ibid.; accord State v. Bey II, supra, 112 N.J. at 75, 548 A.2d 846; State v. Corsaro, supra, 107 N.J. at 348, 526 A.2d 1046. Thus, any irregularity is presumptively prejudicial. State v. Corsaro, supra, 107 N.J. at 346, 526 A.2d 1046 (citation omitted); State v. Auld 2 N.J. 426, 432, 67 A.2d 175 (1949). The prejudicial impact of juror misconduct of the magnitude involved in this death penalty ease is virtually irrebuttable. A new death penalty trial is required.
VII
Next we address defendant’s argument that the trial court erred in submitting the “murder-to-avoid-apprehension” aggravating factor to the jury because there was insufficient evidence to support a finding that the factor existed. See N.J.S.A. 2C:11-3c(4)(f). Defendant insists that the testimony of Christopher Forston was direct evidence that the victim was shot because she would not cooperate. That same argument was rejected in State v. Hightower, supra, 120 N.J. at 420, 577 A.2d 99.
The murder-to-avoid apprehension factor focuses on the reason that a defendant killed his or her victim. It requires proof that “[t]he murder was committed for thé purpose of escaping detection, apprehension, trial, punishment or confinement for another offense committed by the defendant or another.” N.J.S.A. 2C:11-3c(4)(f). The fact that a murder occurs contemporaneously with the witnessed underlying crime does not mitigate the evil of killing a potential witness. State v. Hightower, supra, 120 N.J. at 421, 577 A.2d 99. As this Court held, that aggravating factor may be submitted to the jury when
the State has produced sufficient evidence on which a jury can reasonably conclude • that at least one of the motives of the defendant in killing his or her victim was to *268eliminate a witness or avoid subsequent apprehension and prosecution for criminal acts. Such evidence may be either direct or circumstantial.
[State v. Martini, supra, 131 N.J. at 282-83, 619 A.2d 1208 (emphasis added); accord State v. DiFrisco, supra, 137 N.J. at 501, 645 A.2d 734.]
Applying that standard to the evidence produced by the State in the present case, we hold that the trial court properly found that there was sufficient evidence on which the jury could conclude that at least one of the motives for defendant’s killing of the victim was to eliminate a witness or avoid apprehension. The following evidence bolstered a finding that the c(4)(f) aggravating factor existed: (1) after entering the store, defendant waited for the few customers inside to leave before committing the crime; (2) defendant turned the store sign from “open” to “closed” after all of the customers had exited the store to preclude other customers from entering; (3) defendant fired the first shot within inches of the victim’s heart; (4) defendant fired the second shot after the victim began to holler; (5) defendant fired the third shot into the victim’s brain; and (6) the robbery was committed during the day. Although we do not reject the possibility that one of the reasons defendant shot the victim may have been because he had become angry and frustrated due to her lack of cooperation, we find a substantial rational basis in the evidence for a reasonable jury also to infer that the defendant shot the victim so she would not live to testify as a witness against him or to assist the State in apprehending and prosecuting him.
We do, however, agree with defendant’s argument that the jury charge on the c(4)(f) aggravating factor was insufficient in light of the c(4)(g) felony murder aggravating factor. We need not,- however, address the issue of whether the charge was so deficient as to require reversal. On the retrial, the trial judge must properly instruct the jury regarding this aggravating factor. Further, we remind trial courts that when essentially the same evidence is used to support both the c(4)(f) and c(4)(g) aggravating factors, the guidelines set forth in Bey II must be followed and the jury must be warned not to double count evidence. State v. Hightower, supra, 120 N.J. at 422, 577 A.2d 99; see State v. Rose, *269112 N.J. 454, 526-27, 548 A.2d 1058 (1988); State v. Bey II, supra, 112 N.J. at 174-77, 548 A.2d 887.
VIII
We vacate defendant’s death sentence and remand to the Law Division for a new penalty trial.
HANDLER, J., has filed a separate opinion concurring in part and dissenting in part, Point I of which O’HERN, J., joins.