This is an appeal from a judgment which the appellant claims should have been barred by the Utah statute of limitations. Plaintiffs brought this action against Rena Chynoweth for the wrongful death of Ru-lon Allred. In rulings on a motion to dismiss and a motion for summary judgment, *529the district court concluded the statute of limitations did not bar the plaintiffs’ cause of action. The court also granted summary judgment for the plaintiffs on the specific elements of the wrongful death claim. The case proceeded to trial on damages, and the jury awarded the plaintiffs $52,125,000. The defendant now appeals the district court’s holding that the discovery rule applied to toll thé statute of limitations until 1990. We affirm.
Rena Chynoweth was a member of the Church of the Lamb of God, a polygamist group led by Ervil LeBaron. On May 10, 1977, Ms. Chynoweth and other LeBaron “family” members, apparently acting at the direction of Mr. LeBaron, killed Rulon Allred, the leader of a rival polygamist group. Local police arrested Ms. Chynow-eth in November, 1978, and in December, 1978, after preliminary hearings, the state court ordered her to stand trial.
Because of the disguise Ms. Chynoweth wore to commit the murder, witnesses were unable to identify her as the killer. Ms. Chynoweth also testified at trial and lied about her involvement in the crime. Ms. Chynoweth and her coconspirators were acquitted in March, 1979.1
After the criminal trial, Ms. Chynoweth went into hiding, moving often and concealing her identity. However, in 1990, she published a book, Blood Covenant, in which she admits shooting Rulon Allred. Since publishing the book, Ms. Chynoweth has made several public appearances to promote it and has openly recounted the details of the murder and her false testimony at trial. In July, 1990, the plaintiffs filed this diversity action.
Ms. Chynoweth moved to dismiss the wrongful death claims based on the Utah statute of limitations, but the district court denied the motion. In response to the plaintiffs’ subsequent summary judgment motion, the defendant again argued the statute of limitations barred the cause of action. Specifically, she asserted disputed facts existed regarding when the plaintiffs knew or had reason to know she was involved in the murder. Ms. Chynoweth did not dispute either the facts of the murder or her involvement in it.
The district court granted plaintiffs’ motion, leaving for trial only the question of damages. Ms. Chynoweth declined to participate in that proceeding. Following entry of final judgment, she brought the matter before us in this appeal.
Because the question of plaintiffs’ knowledge of their cause of action is of paramount concern, we begin our review mindful of the proposition that “the issue of when a plaintiff knew or with reasonable diligence should have known of a cause of action is a question of fact.” Maughan v. SW Servicing, Inc., 758 F.2d 1381, 1387 (10th Cir.1985). In this instance, however, the trial court determined on summary judgment the essential facts were undisputed, the discovery rule applied, and no reasonable plaintiff could have known of the cause of action prior to 1990. Therefore, we review the summary judgment decision de novo. See Applied Genetics Int’l, Inc. v. First Affiliated Sec., Inc., 912 F.2d 1238, 1241 (10th Cir.1990) (court must review grant or denial of summary judgment de novo, applying same legal standard as district court) (citing Barnson v. United States, 816 F.2d 549, 552 (10th Cir.), cert. denied, 484 U.S. 896, 108 S.Ct. 229, 98 L.Ed.2d 188 (1987)).
Utah law establishes a two-year statute of limitations for wrongful death actions. Utah Code Ann. § 78-12-28(2). The state general rule is “that a cause of action accrues upon the happening of the last event necessary to complete the cause of action.” Myers v. McDonald, 635 P.2d 84, 86 (Utah 1981). Under this rule,, a plaintiff’s mere ignorance of the existence of a cause of action will not prevent the running of the limitations period. The intention behind this precept is “ ‘to promote justice by preventing surprises through the revival of claims that have been allowed to slumber until evidence has been lost, mem*530ories have faded, and witnesses have disappeared.’ ” Id. (quoting Order of R.R. Telegraphers v. Railway Express Agency, Inc., 321 U.S. 342, 348-49, 64 S.Ct. 582, 586, 88 L.Ed. 788 (1944)).
The Utah Supreme Court has recognized exceptions to the general rule, however. In three circumstances, the Utah courts apply the discovery rule to toll the statute of limitations “ ‘until the discovery of facts forming the basis for the cause of action.’ ” Warren v. Provo City Corp., 838 P.2d 1125, 1129 (Utah 1992) (quoting Myers, 635 P.2d at 86); O’Neal v. Division of Family Servs., 821 P.2d 1139, 1143 (Utah 1991). Those situations are:
[1] ... where the discovery rule is mandated by statute; (2) ... where a plaintiff does not become aware of the cause of action because of the defendant’s concealment or misleading conduct; and (3) ... where the case presents exceptional circumstances and the application of the general rule would be irrational or unjust, regardless of any showing that the defendant has prevented the discovery of the cause of action.
Warren, 838 P.2d at 1129 (footnotes omitted); see also O’Neal, 821 P.2d at 1143.
Because the wrongful death statute under which this action was instituted does not specifically provide for a delay of the accrual of the cause of action, only the concealment and exceptional-circumstances versions of the discovery rule are at issue here. For either version to apply, the plaintiffs must not have learned of the facts giving rise to the cause of action before the end of the limitations period. Atwood v. Sturm, Ruger & Co., 823 P.2d 1064, 1065 (Utah 1992) (citing Brigham Young Univ. v. Paulsen Constr. Co., 744 P.2d 1370, 1374 (Utah 1987)); O’Neal, 821 P.2d at 1144.
Under the concealment version of the discovery rule, a defendant who misleads the plaintiff or “causes a delay in the bringing of a cause of action is estopped from relying on the statute of limitations as a defense to the action.” Warren, 838 P.2d at 1130. However, to invoke the concealment version, a plaintiff must show he or she acted reasonably in not bringing the suit within the statutory period. The limitations period begins to run when the plaintiff has actual knowledge of the facts of the cause of action. Vest v. Bossard, 700 F.2d 600, 611 (10th Cir.1983) (McKay, J., concurring).
The exceptional-circumstances version of the discovery rule tolls the statute of limitations in cases where enforcement of the limitation would be irrational or unjust. This version requires a plaintiff to demonstrate he or she exercised due diligence in discovering the cause of action. Becton Dickinson & Co. v. Reese, 668 P.2d 1254, 1257 (Utah 1983); see Myers, 635 P.2d at 87. If the plaintiff can prove due diligence, the court then determines the application of the discovery rule based on a balancing test: whether “the hardship the statute of limitations would impose on the plaintiff in the circumstances of th[e] ease outweigh[s] any prejudice to the defendant from difficulties of proof caused by the passage of time.” Myers, 635 P.2d at 87; see Vest, 700 F.2d at 602 (discovery rule applies when policy against stale claims is outweighed by unique circumstances of plaintiffs’ hardship); Klinger v. Kightly, 791 P.2d 868, 872 (Utah 1990).
In this case, the district court determined the facts justify/ápplication of the discovery rule based/m both the concealment and exceptional-circumstances versions of the rule. The bourt concluded Ms. Chynoweth attempted to mislead the police and the state .court during the investigation and criirimal trial. The court also held application of the statute of limitations would be irrational and unjust to the plaintiffs. In the district court’s view, no reasonable plaintiff, exercising due diligence, could have discovered the existence of a claim against the defendant before Ms. Chynow-eth’s public disclosure of her involvement.
On appeal, Ms. Chynoweth first argues the discovery rule does not apply because the plaintiffs knew or should have known of the injury and its cause before the statute of limitations expired. To support her argument, she notes two facts: first, in December, 1977, the state court determined *531four coconspirators should stand trial; second, in December, 1978, after a probable cause hearing, the state court found sufficient cause to believe Ms. Chynoweth committed the murder and bound her over for trial.
Ms. Chynoweth asserts these facts demonstrate the plaintiffs were aware of the nature of the injury giving rise to the action in 1977, and, after the probable cause hearings in 1977 and 1978, should have been aware of the cause of that injury. Thus, they should have had knowledge of the cause of action before the limitations period ended in 1979. At the very least, Ms. Chynoweth argues, the plaintiffs’ cause of action accrued in 1980 when Ervil LeBaron was convicted of the murder.
Ms. Chynoweth relies on two cases to support her argument. In Atwood, 823 P.2d at 1064, the plaintiff was injured when his gun fell and discharged. The plaintiffs attorney informed him, before the statute of limitations ran out, that he might have a cause of action against the defendant. However, the plaintiff failed to file within the statutory period and gave no reason for his delay. Based on these facts, the Utah Supreme Court refused to apply the discovery rule. Id. at 1065. Similarly, in Brigham Young Univ. v. Paulsen Constr. Co., 744 P.2d 1370, 1374 (Utah 1987), the court held the facts did not warrant application of the discovery rule since the plaintiff learned the defendant contractor’s work caused damage to its buildings over three years before the limitations period ended. Ms. Chynoweth correctly cites these cases for the proposition that the discovery rule does not apply when a plaintiff became aware of the cause of action before the expiration of the limitations period. In relying on these cases, however, Ms. Chy-noweth does not consider the unusual effect her subsequent acquittal has on her theory.
Momentarily putting aside consideration of the two versions of the discovery rule, we believe the threshold issue here is whether a reasonable plaintiff would have known a cause of action existed against Ms. Chynoweth after a jury acquitted her of the murder. Although the plaintiffs in this case knew Rulon Allred was murdered and, after the probable cause hearings, had reason to suspect Ms. Chynoweth committed the murder, the jury’s acquittal logically would have substantially undercut that suspicion, if not eliminated it altogether. At least plaintiffs would no longer have had any incentive to pursue a claim against Ms. Chynoweth.
Ms. Chynoweth’s argument that the plaintiffs should have known of the cause of action in 1980, when Ervil LeBaron was convicted, is also without merit in a case against her. She does not assert new information came to light in Mr. LeBaron’s trial to indicate she committed the murder. Instead, Ms. Chynoweth claims the plaintiffs’ failure to sue Ervil LeBaron prevents them from stating a claim against her.
The defendant next argues, even if the discovery rule applies, the plaintiffs failed to exercise due diligence to discover the cause of action.2 To support this argument, Ms. Chynoweth asserts at least two coconspirators testified at the probable cause hearings concerning her involvement in the crime. This testimony, she contends, would have led a diligent plaintiff to file an action against her. In addition, at the time the state court ordered her to stand trial, five months remained before the expiration of the limitations period. Finally, she claims the plaintiffs’ failure to initiate any investigation, or at least consult with a lawyer, after Mr. LeBaron’s conviction indicates they did not diligently pursue their claims.
The district court determined, as a matter of law, the plaintiffs could not have discovered the facts surrounding Rulon Allred’s death. The court found the plaintiffs reasonably relied on the jury's determination in the criminal case that Ms. Chy-*532noweth was not guilty.3
We hold the district court correctly concluded both versions of the Utah discovery rule apply to this case. Ms. Chynoweth’s use of a disguise in committing the murder and, more importantly, her false testimony at trial misled the criminal jury and the plaintiffs. After lying at trial and convincing a jury to acquit her, she cannot argue the plaintiffs should have known a cause of action existed based on probable cause hearings. Moreover, a reasonable plaintiff, exercising due diligence, would not have been motivated to pursue an investigation against a person who had been found not guilty on the evidence presented in this instance. We are satisfied the facts demonstrating her culpability could not be, and were not, discovered until Ms. Chynoweth admitted the crime in her book.
Even under the most cautious view, the jury's verdict in the criminal case has to be an exceptional circumstance which would have deterred plaintiffs from investigating their cause of action. A suggestion that plaintiffs should have pursued an action against Ms. Chynoweth regardless of the verdict would improperly encourage people to file apparently groundless suits simply to prevent the running of the statute of limitations. See Foil v. Ballinger, 601 P.2d 144, 148 (Utah 1979) (“[T]o adopt a construction of [a statute] that encourages a person who experiences an injury, dysfunction or ailment, and has no knowledge of its cause, to file a lawsuit ... to prevent a statute of limitations from running is not consistent with the unarguably sound proposition that unfounded claims should be strongly discouraged.”).
Ms. Chynoweth’s active concealment of her role and the hardship the statute of limitations would impose on the plaintiffs justify application of both versions of the discovery rule. Moreover, the equities on plaintiffs’ side certainly outweigh any prejudice to the defendant from the passage of time.
Because Ms. Chynoweth does not contest liability, she cannot assert the delay has impaired her ability to present a defense. Her only claim is that plaintiffs should not be able to recover because she successfully prevented them from discovering her liability for many years. That is not within the ambit of equitable concern which motivates the adoption of statutes of limitations.
AFFIRMED.
. In May, 1980, Mr. LeBaron was found guilty of the murder and sentenced to prison. He died in prison of natural causes in August, 1981.
. As already noted,- the question of plaintiffs’ diligence goes only to the issue of exceptional circumstances and is not part of the concealment paradigm.
. To support its conclusion, the court looked to Williams v. Hartje, 827 F.2d 1203, 1205 (8th Cir.1987), in which the plaintiffs’ family member, Williams, died in jail. Another inmate testified at a coroner’s inquest that he did not see or hear anything out of the ordinary. The coroner’s jury determined Williams’ death was not the result of criminal action. Twenty-four years later, the inmate revealed that he lied at the coroner’s inquest; he saw two guards beat Williams, but, because of one of the guard’s threats, he testified he had not seen anything. The Eighth Circuit affirmed the district court’s denial of the defendants’ motions to dismiss and for summary judgment based on the statute of limitations. The court stated ”[i]t cannot be said that the plaintiffs failed to exercise due diligence in not discovering this alleged coverup, because their only possible source of information was locked up in the mind of [the inmate] and remained there until he was ready to come forward with his story." Id. at 1206.