This is the companion case to Harvey v. State, 774 P.2d 87 (Wyo.1989). Appellant Everett William Phillips appeals his convictions of kidnapping and first-degree sexual assault.1 Appellant raises several issues upon appeal, but, as in Harvey, we find that the dispositive issue is whether, under the circumstances of this case, appellant was denied the right to a speedy trial.
We reverse.
Appellant was charged and convicted identically with his codefendant, Jetty Lee Harvey, in connection with the January 5, 1986, abduction and rape of a Rock Springs woman. A third defendant, David Swazo, who was the actual perpetrator of the sexual assault, was convicted upon a guilty plea, and he testified against appellant and Harvey at trial. The facts of the offenses, as presented at trial by the State and ac*120cepted by the jury, are summarized in Harvey and need not be repeated here. Of additional note, however, are the facts that appellant was the owner and driver of the vehicle in which the sexual assault occurred and that appellant was not arrested by the police upon their intervention in the offenses, as were Harvey and Swazo, because the victim did not initially implicate appellant in the crime.
Although appellant was tried jointly with his co-defendant, Harvey, on identical charges stemming from the same incident and although the total period of delay in each case is the same, the procedural sequence of events differs in each case in certain respects. Thus, in order to properly evaluate appellant’s lack of speedy trial claim, it is necessary that we trace the progression of this case from the complaint and arrest through trial, although often these steps overlap with those outlined in Harvey. The offenses occurred on January 5, 1986. Appellant was arrested on January 9, 1986, pursuant to a complaint issued on that date and amended on January 10.2 On January 16, 1986, through counsel, appellant filed a waiver of both his initial appearance and a speedy preliminary hearing, and a preliminary hearing was scheduled by the county court for February 27, 1986. On February 7, 1986, upon a motion for continuance filed by the State, the preliminary hearing was rescheduled for April 15,1986. Appellant, on February 20, 1986, moved for a continuance, and the preliminary hearing was reset for May 1, 1986. On April 29, 1986, the State again obtained a continuance, and the preliminary hearing was rescheduled for July 1, 1986. On July 1, the preliminary hearing was held, and appellant was bound over to district court.
The information was filed in the district court on July 14, 1986, and an arraignment was also held on that date, in which appellant entered a plea of not guilty. On the date of the arraignment, appellant filed a motion to dismiss, a motion for a bill of particulars, and a motion for discovery. The district court did not rule on these motions at that time.
The ensuing five months are notable simply by the fact that no activity of record occurred for those five months. The next event of record is a letter from the district court, filed December 5, 1986, informing counsel that the court had consolidated the cases of appellant and his co-defendants, Harvey and Swazo, and that trial was set for January 6,1987. On December 9, 1986, the State obtained a continuance. This fact, as in the Harvey case, is not shown in the record, but the State has acknowledged in its appellate brief that it obtained the continuance.3 As in Harvey, we will accept as a conceded point the State’s acknowl-edgement that it obtained this continuance, thus accounting for the otherwise inexplicable fact that trial was not held on January 6, 1987, as scheduled.
On December 10, 1986, appellant filed a motion for severance of his trial from that of his co-defendants. On December 15, 1986, the district court issued an order establishing a briefing schedule on this motion and on appellant’s pending motions submitted at the previous July arraignment. Pursuant to this order, appellant had twenty days in which to file his brief, and the State was given fifteen days thereafter to file its reply brief. Appellant filed his motions’ brief on December 29, 1986, and the State’s brief was due on January 19, 1987. On February 3, 1987, pursuant to a motion by the State, the district court granted the State an extension until March *1212,1987, in which to file its brief. From the fact that this motion and order are on the same document, obviously prepared by the prosecuting attorney, and because this document does not indicate that appellant was served with a copy of the motion, it would appear that appellant aptly characterizes this motion and order as having been obtained ex parte. The State’s reply brief was eventually filed on April 15, 1987. On April 21, 1987, appellant filed an objection to the State’s brief, requesting that it be stricken as untimely and requesting that appellant’s motions be granted. Apparently, the district court issued a letter ruling on appellant’s motions on April 30, 1987, as this fact is referred to by both parties in their briefs, though the letter ruling is not in the record. The district court’s disposition of these motions is not shown, although the State subsequently provided a bill of particulars and the motion to sever was denied in pretrial conference.
The district court also apparently sent notice to counsel on June 2, 1987, of the July 21, 1987, trial setting, though again this notice is not in the record but is referred to by both parties in their briefs. On July 6, 1987, appellant filed a motion to dismiss on speedy trial grounds, and briefs on that issue were filed by both parties. The trial began on July 21, 1987, and, in a pretrial chambers conference, the district court denied appellant’s speedy trial motion. After a three-day trial, the jury returned a verdict of guilty on both charges. Appellant was sentenced on October 22, 1987, to two concurrent terms of not less than twenty years nor more than thirty years.
The right to a speedy trial is guaranteed by both the Sixth Amendment to the United States Constitution and article 1, section 10 of the Wyoming Constitution.4 In assessing appellant’s denial of a speedy trial claim, we are guided in this case, as we were in Harvey, by Rule 204 of the Uniform Rules for the District Courts of the State of Wyoming in conjunction with the four-part balancing test enunciated by the United States Supreme Court in Barker v. Wingo, 407 U.S. 514, 92 S.Ct. 2182, 33 L.Ed.2d 101 (1972), and followed by this Court in a long series of cases beginning with Cosco v. State, 503 P.2d 1403 (Wyo.1972), cert. denied 411 U.S. 971, 93 S.Ct. 2164, 36 L.Ed.2d 693 (1973).
Rule 204(b) directs that “[a] criminal charge shall be brought to trial within 120 days following the filing of information or indictment.” The rule provides that certain periods are to be excluded from the computation of the 120-day period, including delays caused by proceedings related to the defendant’s mental illness or deficiency, proceedings on another charge, the defendant’s change of counsel or application therefor, continuances granted to the defendant, and continuances granted to the prosecution — if the defendant expressly consents, if the State’s evidence is unavailable despite the exercise of due diligence, or if they are required in the due administration of justice and the defendant will not be substantially prejudiced. Rule 204(c) and (d). See also Harvey, 774 P.2d at 94. This Court has held that Rule 204 is not an exclusive or mandatory test but rather that it is advisory and that it constitutes another factor to be considered in conjunction with the balancing test from Barker, 407 U.S. 514, 92 S.Ct. 2182. Harvey, 774 P.2d at 93-94; Caton v. State, 709 P.2d 1260 (Wyo.1985). Thus, we will consider the provisions of Rule 204, as they relate to this case, within the context of the balancing test analysis. Under the Barker balancing test, we examine speedy trial challenges in light of the following four factors: (1) length of the delay; (2) reason for the delay; (3) the defendant’s assertion of his speedy trial right; and (4) prejudice to the defendant. Barker, 407 U.S. at 530, 92 S.Ct. at 2191; Estrada v. State, 611 P.2d 850, 852 (Wyo.1980). In considering whether a speedy trial violation has occurred, all the factors are to be considered and balanced in relation to all relevant circumstances. Moore v. Arizona, 414 U.S. *12225, 94 S.Ct. 188, 38 L.Ed.2d 183 (1973); Heinrich v. State, 638 P.2d 641 (Wyo.1981).
LENGTH OF DELAY
We begin our examination of the length of the delay in light of the 120-day time limitation established by Rule 204(b). Pursuant to Rule 204(b), the relevant time period for a speedy trial analysis runs from the date of the information to the date of trial. Here, the information was filed on July 14,1986, and trial commenced on July 21, 1987, 372 days later. Although Rule 204(c) provides that various periods are to be excluded from the computation of the time period, none of the allowable exclusions are found in the record in this case. Appellant did not seek any continuances during this time period, and the December 9, 1986, continuance sought and obtained by the State appears to have been accomplished without appellant’s prior knowledge or consent. This continuance, consequently, does not qualify for exclusion, and, under the Rule 204(c) analysis, the length of delay remains at 372 days.5 From the standpoint of Rule 204, we see that the delay in this case exceeded the prescribed 120-day time period by more than three times. While Rule 204 is advisory rather than mandatory, as we noted in Harvey, the delay in this case is more than sufficient to trigger further analysis of the other factors. Harvey, 774 P.2d at 94; Caton, 709 P.2d at 1265.
The length of the delay in the instant case is considerably longer when evaluated ■ under a constitutional analysis wherein the speedy trial clock starts to run upon either arrest or the filing of the complaint. United States v. Marion, 404 U.S. 307, 92 S.Ct. 455, 30 L.Ed.2d 468 (1971); Caton, 709 P.2d 1260. See also Dillingham v. United States, 423 U.S. 64, 96 S.Ct. 303, 46 L.Ed.2d 205 (1975) (Sixth Amendment activated when a criminal prosecution has begun and extends to those who have been accused). Here, the original complaint was filed on January 9, 1986, and appellant was apparently arrested on that date or shortly thereafter. See supra note 1. The elapsed time between the filing of the complaint and appellant’s trial was, accordingly, 558 days, or more than one and one-half years. Although we have stated that no specific length of delay automatically creates a constitutional speedy trial violation, Caton, 709 P.2d at 1264, we have also said:
[W]hen the delay is so protracted as to be presumptively prejudicial, it is a triggering mechanism, which requires “inquiry into the other factors that go into the balance.”
Phillips v. State, 597 P.2d 456, 460 (Wyo.1979) (quoting Barker, 407 U.S. at 530, 92 S.Ct. at 2192). In the instant case, the delay of 558 days from the filing of the complaint to the trial is so protracted as to be presumptively prejudicial. Inquiry into the other factors, therefore, is required, and the excessive delay must be weighed heavily against the State in the final analysis.
REASON FOR DELAY
We have already determined that none of the period between the filing of the information and the trial is excludable delay under Rule 204(c). We now look at the entire period from the filing of the complaint to trial to determine if any of this period reflects delays attributable to appellant or excusable for any other reason. Delays attributable to á defendant may dis-entitle him to speedy trial safeguards. Harvey, 774 P.2d at 94; Cherniwchan v. State, 594 P.2d 464, 468 (Wyo.1979). The State argues that appellant agreed to the first “seven” months of delay from the time of the original complaint until the filing of the information — a period of actually only six months. This contention overstates the facts, although appellant was responsible for some of the delay in this initial period. Appellant initially waived his right to a speedy preliminary hearing, and both appellant and the State sought *123continuances causing delay, reasonably attributable to both, up through the continuance obtained by appellant on February 20, resetting the preliminary hearing for May 1, 1986. On April 29, the State again obtained a continuance, resulting in the resetting of the preliminary hearing from May 1 to July 1, 1986. There is nothing in the record indicating that appellant agreed to, or had an opportunity to object to, this continuance. This final two months of delay in getting to the preliminary hearing is attributable solely to the State.
For five months after the July 14, 1986, information and arraignment absolutely nothing of record occurred in the case. The State does not attempt to justify or even to explain this period. After the district court notified the parties on December 5, 1986, that trial was set for January 6, 1987, the State immediately sought and obtained a continuance. Since there is no record of this continuance, since we must rely upon the State’s concession that it obtained the continuance, and since it does not appear that appellant had prior knowledge or opportunity to object to the continuance, we can only attribute the delay occasioned by this continuance to the State.
Given that the State had just obtained a continuance of the January 6, 1987, trial date, we are reluctant to ascribe any delay to appellant resulting from the briefing upon appellant’s motions ordered by the district court on December 15, 1986. It is not at all clear that the district court would have delayed trial for this purpose absent the continuance obtained by the State. In any event, pursuant to the briefing schedule, appellant promptly filed his brief, several days ahead of the deadline imposed by the court. The State’s brief was due on January 19, 1987. This one-month period for briefing can arguably be attributed to appellant. The ensuing three-month period required by the State to file its brief, however, resulting from missed deadlines and extensions granted, is solely attributable to the State and its lackadaisical approach to prosecuting this case, as is the balance of the time required to bring the case to trial, all of which was a direct result of the December continuance obtained by the State.
The State additionally argues that much of the delay can be justified as necessary due to the State’s attempt to obtain the testimony of Swazo against appellant and as a result of a crowded docket. The State made the same arguments in the Harvey case, and we reject them here for the same reasons as we did in that case— lack of record support. As in Harvey, we note that the State did not seek a continuance on either of these grounds. The record does indicate that Swazo was convicted upon a guilty plea prior to appellant’s trial and that he testified for the State against appellant at trial. While the Supreme Court in Barker, 407 U.S. at 534, 92 S.Ct. at 2194, observed that perhaps some delay is permissible for the prosecution to obtain the testimony of a co-defendant, on this record we cannot determine how much delay, if any, was occasioned by plea negotiations with Swazo. The only indication in the record of a docket problem is contained in the State’s February 3, 1987, motion requesting an extension of time for filing its already overdue brief. In seeking the extension, the State cited its need to prepare for an upcoming trial. According to the dates the State listed for this assertedly conflicting trial, however, it appears that the State did not file its brief on appellant’s motions until two months after that trial. On this record, we cannot attribute any delay to an overcrowded docket.
Of the eighteen months taken to bring appellant to trial following the initial complaint, appellant was jointly responsible for three, or perhaps four, months of the delay, with a balance of at least fourteen months for which the State has offered no plausible explanation or justification. We are in agreement with appellant’s contention that, once the case reached the district court, virtually none of the delay can be properly attributed to appellant, in that appellant filed all motions and briefs in a timely manner, even ahead of deadlines, and did nothing to prolong the prosecution of the case. The State has the burden to *124prove that delays in bringing a defendant to trial are reasonable and necessary. Estrada, 611 P.2d 850; Stuebgen v. State, 548 P.2d 870 (Wyo.1976). In this ease, as in Harvey, the State has failed to meet its burden. Our remarks in Harvey regarding the reason for delay are equally appropriate in the instant case:
While it is recognized that neutral or innocent unnecessary delay should be weighed less heavily against the State than deliberate unnecessary delay, Caton, 709 P.2d at 1265; Estrada, 611 P.2d 850; Barker, 407 U.S. 514 [92 S.Ct. 2182], it is also recognized that such delay must nevertheless be considered, because the government, rather than the defendant, bears the ultimate responsibility for such circumstances. Estrada, 611 P.2d at 854; Barker, 407 U.S. at 531 [92 S.Ct. at 2192]. Here, we are unable to determine whether the delay was in fact neutral as opposed to deliberate, although nothing in the record indicates any sinister motive on behalf of the State. What we do find in this case, however, is simply no reason or justification for the delay, and we cannot say that the State made a good faith effort to bring appellant to trial as quickly as possible. See Heinrich, 638 P.2d at 644.
Harvey, 774 P.2d at 95. As in Harvey, we conclude that considerations of the reason for delay weigh substantially in appellant’s favor in the balancing test.
DEFENDANT’S ASSERTION OF HIS RIGHTS
It is not essential that a defendant assert his speedy trial right as a prerequisite to an ultimate conclusion that a speedy trial violation has occurred, but it is a relevant factor to consider. Estrada, 611 P.2d at 854; Hurst v. State, 563 P.2d 232 (Wyo.1977). The State urges, with respect to this factor, that appellant made no objection to the December 9, 1986, continuance obtained by the State. As mentioned previously, it appears that the continuance was granted without appellant's prior knowledge and opportunity to object. Nevertheless, appellant did not file his motion to dismiss on speedy trial grounds until July 6, 1987, two weeks before trial. A defendant, however, has no duty to bring himself to trial. Barker, 407 U.S. at 527, 92 S.Ct. at 2190; Dickey v. Florida, 398 U.S. 30, 90 S.Ct. 1564, 26 L.Ed.2d 26 (1970). Thus, while this factor cannot be said to weigh in appellant’s favor, neither can it be seen to weigh against him, as he had no notice and opportunity to object to the trial continuance obtained by the State or to the extension granted the State in motions briefing, and appellant ultimately did assert his right prior to trial.
PREJUDICE TO DEFENDANT
Prejudice to the defendant is the final factor for consideration in the balancing test. It is not necessary that prejudice be affirmatively shown in order to prove a violation of the constitutional right to a speedy trial, Moore, 414 U.S. at 26, 94 S.Ct. at 189, and Heinrich, 638 P.2d at 644, but it is an important factor to consider. Caton, 709 P.2d at 1266; Grable v. State, 649 P.2d 663, 671 (Wyo.1982). Prejudice to the defendant may consist of: (1) lengthy pretrial incarceration; (2) pretrial anxiety; and (3) impairment of defense. Barker, 407 U.S. at 532, 92 S.Ct. at 2192. See also Heinrich, 638 P.2d 641; and Estrada, 611 P.2d 850.
In Harvey, 774 P.2d at 96, we held that the delay of approximately eighteen months in that case was sufficiently lengthy to be presumptively prejudicial with respect to pretrial anxiety and related concerns (including the defendant’s social relations, freedom of movement, and anxiety over public accusation), citing Dickey, 398 U.S. at 39, 90 S.Ct. at 1569 (Brennan, J., concurring); Caton, 709 P.2d 1260; and Cherniwchan, 594 P.2d 464. The same can be said regarding the equivalent delay in this case. The other two aspects of prejudice, as in Harvey, do not appear to be present in this case. Appellant was incarcerated only briefly after arrest. In his pretrial brief supporting his motion to dismiss for lack of speedy trial, appellant asserted that he was having difficulty locating two witnesses, but this is not borne out elsewhere in the record, nor was any such *125difficulty shown to be a function of the delay. We conclude, therefore, as we did in Harvey, that appellant was presumptively prejudiced by the lengthy delay but that the prejudice was only minimal, and this factor weighs only slightly in appellant’s favor in the overall balancing test.
BALANCING THE FACTORS
This case is very similar to the companion case of Harvey in which we concluded that a speedy trial violation had occurred. Here, the first two factors— length of delay and reason for delay— weigh decisively in appellant’s favor. Although appellant did not actively assert his speedy trial right until shortly before trial, he did raise the issue, and this factor does not weigh against appellant to any significant extent. The prejudice factor leans slightly in appellant’s favor as a result of the presumption of prejudice associated with excessive delay such as occurred in this case. Balancing the four factors together, we conclude that, as we did in Harvey, a violation of appellant’s speedy trial right has occurred. The length of the delay and the lack of any reasonable justification for it are sufficiently decisive in this case, even though the prejudice to appellant was relatively minor and he did not timely assert his right.
The instant case may be somewhat closer than Harvey by virtue of the fact that appellant was responsible for some of the delay in getting to the preliminary hearing and because appellant was not as diligent as Harvey in asserting his right. The differences in the two cases, however, are mostly illusory. In each case, there occurred a delay from the time of complaint and arrest until trial of one and one-half years attributable primarily to the State and the trial court. In each case, the State has failed to meet its burden of proving that the excessive delay was necessary or reasonable. Estrada, 611 P.2d 850. In each case, the delay exceeded the 120-day guideline of Rule 204(b) several times over. In neither case are we able to say that the State made a good faith effort to bring the defendant to trial as soon as possible. See Heinrich, 688 P.2d 641.
In Harvey, we discussed the fact that the only remedy for a violation of the constitutional right to a speedy trial is dismissal of the information. Harvey, 774 P.2d at 97. This is obviously an extreme remedy, particularly where, as here, appellant was found guilty by a jury of a serious crime. It is, however, the only possible remedy. Barker, 407 U.S. at 522, 92 S.Ct. at 2187. If we intend to honor and preserve the right, as constitutionally guaranteed for the protection of all society from the danger of lingering governmental accusation without the benefit of trial, we must enforce the right in difficult cases such as this. See Harvey, 774 P.2d at 97 (extended examination of the necessity for and rationale underlying the remedy of dismissal).
For the reasons stated in this opinion, and with reference to the reasoning incorporated in the companion case of Harvey, 11A P.2d 87, we reverse appellant’s convictions and remand to the district court with instructions to dismiss the information.
URBIGKIT, J., filed a specially concurring opinion.
THOMAS, J., filed a dissenting opinion in which GOLDEN, J., joined.
GOLDEN, J., filed a dissenting opinion in which THOMAS, J., joined.
. As in the Harvey case, appellant was charged alterantively on both crimes as either a principal or an aider and abettor. Also as in Harvey, there is a discrepancy between the verdict and the judgment and sentence as to whether appellant was convicted as a principal or as an accessory. This discrepancy is raised as an issue by appellant, but our disposition of the speedy trial issue precludes the necessity of addressing this issue. See Harvey, 774 P.2d at 89, n. 1.
. Appellant, in his brief, lists the date of arrest as being January 14, 1986. Testimony in the record, however, places the date of arrest at January 9, 1986.
. Although not a matter of record, appellant attached to his brief a copy of a letter from the prosecuting attorney to defense counsel dated December 9, 1986, which clarifies what occurred. In this letter, the prosecuting attorney informed defense counsel that: "I have this date spoken with Judge Hamm and have continued the above named matters from January 6, 1987 for jury trial.” The letter explains that the new county attorney would take office on January 5, 1987, and that the January 6 trial setting "would place too heavy a burden on both Defense and State’s attorneys." Appellant's characterization of this continuance as ex parte would appear to be accurate.
. The law with respect to the right to a speedy trial is explored in depth in the companion case of Harvey. Thus, the analysis and citation to authority will be somewhat abbreviated in the instant case, and reference to Harvey is suggested.
. Other aspects of the reason for delay will be discussed under that general heading in the body of this opinion.