delivered the Opinion of the Court.
The defendant, Paul Chavez, was charged in a criminal complaint in the Las Animas County Court with two counts of sexual assault on a child, section 18-3-405, 8B C.R.S. (1985 Supp.). Nearly two years after the complaint was filed, the defendant moved to dismiss the charges on the ground that he was denied his constitutional right to a speedy trial. The district court granted the motion, and the district attorney appealed. We affirm.
Both the sixth amendment to the United States Constitution and article II, section 16 of the Colorado Constitution guarantee an accused the right to a speedy trial. In addition, the defendant’s constitutional right to a speedy trial is fortified by section 18-1-405, 8B C.R.S. (1986 and 1987 Supp.), and Crim.P. 48(b), which were intended to clarify and simplify the parameters of the constitutional right. Carr v. District Court, 190 Colo. 125, 543 P.2d 1253 (1975).
Section 18-1-405, 8B C.R.S. (1986 and 1987 Supp.), and Crim.P. 48(b), mandate dismissal of pending charges if a defendant is not brought to trial within six months after entry of a plea of not guilty. The prosecution contends that the defendant’s rights to a speedy trial were not abridged in this case because the trial was scheduled within six months after the defendant entered a plea of not guilty. Under the facts of this case, the delay in bringing the defendant to trial must also be judged according to constitutional standards. See Gelfand v. People, 196 Colo. 487, 586 P.2d 1331 (1978).
It is the duty of both the prosecution and the trial judge to secure and protect the defendant’s right to a speedy trial. People v. Colantonio, 196 Colo. 242, 583 P.2d 919 (1978); see II ABA Standards for Criminal Justice, Standard 12-1.2 (2d ed. 1980).
The constitutional right to a speedy trial attaches with the filing of a formal charge. United States v. Marion, 404 U.S. 307, 92 S.Ct. 455, 30 L.Ed.2d 468 (1971); People v. Velasquez, 641 P.2d 943 (Colo.1982). When the constitutional right to a speedy trial is asserted, it is necessary to apply the four-factor ad hoc balancing test which was established in Barker v. Wingo, 407 U.S. 514, 92 S.Ct. 2182, 33 L.Ed.2d 101 (1972). In People v. Small, 631 P.2d 148 (Colo.1981), and People v. Spencer, 182 Colo. 189, 512 P.2d 260 (1973), we relied on the Barker test to determine the speedy trial issue under the Colorado Constitution. The four factors are: the length of delay, the reason for the delay, the defendant’s assertion or demand for a speedy trial, and prejudice to the defendant. Barker, 407 U.S. at 530, 92 S.Ct. at 2192. The burden is on the defendant to prove that he has been denied a speedy trial. People v. Small, 631 P.2d at 154. The Barker balancing test for resolving the constitutional speedy trial issue requires consideration of all of the relevant facts.
The sexual assault in this case allegedly occurred in an elementary school in Trinidad, Colorado. Paul Chavez was an elementary school teacher who was charged with sexually assaulting two of his second-grade pupils. K.M., an eight-year-old girl, told her mother about acts that were committed by the defendant in the classroom and in the adjoining closet. The mother reported the incident to the school principal, Frank Welch. K.M. told her mother that when they were celebrating Valen*377tine’s Day on February 17, 1986, the defendant took four pupils, two boys and two girls, into the closet in the classroom, forced them to undress and then sexually molested them, threatened them with a knife, and told them not to tell what happened in the closet. Welch commenced an investigation and obtained assistance from the Department of Social Services. The four pupils who were allegedly involved and others were interviewed by investigators from the Department of Social Services. Medical examinations of the children did not indicate penetration, although K.M. said that penetration occurred. The investigation culminated in the filing of a criminal complaint on April 17, 1986, charging the defendant with sexual assault on W.B., a boy, and on K.M., a girl, on February 17, 1986. A preliminary hearing, which was scheduled for May 23, 1986, was postponed until video depositions of K.M. and W.B. could be taken pursuant to section 18-3-413, 8B C.R.S. (1986). Defense counsel was denied the right to be present when the video depositions were taken. Copies of the videotapes were made available to defense counsel. The videotaped interviews or depositions, although to a large extent inaudible, were admitted, over objection, at the preliminary hearing on September 4,1986. The county court found probable cause to believe the defendant committed the crimes charged, and the defendant was bound over to the district court for trial and ordered to appear in the district court on September 22, 1986.
Thereafter, an information and a number of motions were filed. The district court determined that K.M. and W.B. were medically unavailable within the meaning of section 18-3-413 and CRE 804(a), and on January 5, 1987, permitted further video depositions to be taken, because the first videotapes were to a large extent inaudible. The defendant’s arraignment was postponed by the district judge, according to his usual practice, until all motions and pretrial matters were determined. The defendant was not arraigned and did not enter his plea of not guilty until December 2, 1987. Trial was then scheduled for March 23, 1988.
The defendant filed a motion to dismiss for denial of a speedy trial on March 21, 1988, and the motion was granted on March 22, 1988. The motion, in essence, asserted six grounds for dismissal:
(1) A transcript of the preliminary hearing could not be obtained because the videotapes were to a large extent inaudible and the testimony of the children was inconsistent with later videotaped depositions.
(2) Dilatory actions of the district attorney and the trial judges’s policy and procedure prevented the defendant from being arraigned in a timely manner.
(3) The delay created prejudice because two key witnesses have forgotten what they said when they were interviewed in March and June of 1986, and were thereafter repeatedly questioned by investigators from the Department of Social Services.
(a) Four pupils were allegedly present when the sexual assault occurred. K.M. and W.B., who were named in the complaint, and P.B. (a boy) and L.T. (a girl).
(b) P.B. in an interview contained in a report dated March 31, 1986, stated that there was nothing to tell “because nothing happened.” He repeated the statement on June 3, 1986. L.T. contradicted the statement of K.M. and W.B.
(c) Both L.T. and P.B. have forgotten what was said in former interviews, but have been questioned many times and have been told by social service investigators how important their testimony is to obtain a conviction.
(4) Frank Welch, the principal of the school, provided a statement on May 29, 1986, which said: “When I talked to K.M. about the incident she stated that she was absent the day that happened but L.T. had told her about it the following day.” During the second videotaping defense counsel was permitted to cross-examine K.M. and she denied making the statement to the principal. Frank Welch died on December 22, 1987, and was a necessary defense witness.
*378(5) The prosecution’s delay in complying with discovery requests prejudiced the defendant. Defense counsel sought copies of the pupils’ statements to Phyllis Moniot, an investigator for the Department of Social Services, and an order was entered for production of the social services file. A note prepared by Phyllis Moniot dated February 27, 1987 stated: “Other handwritten notes, our ROC (record of contact sheets) on W.B.^ K.M., L.T. have been destroyed. These are destroyed after we make summaries in our cases every six months.”
(6) Phyllis Moniot was the main investigator and interviewed the pupils on nine different occasions and obtained significantly different statements with the passage of time.
The trial court, in granting the motion to dismiss, made detailed oral findings before entering a formal order of dismissal. First, the trial judge found that the length of the delay in bringing the defendant to trial was significant and resulted in prejudice to the defendant. Second, the delay was not the result of bad faith. The trial judge’s policy was to not take a plea until all pretrial matters were concluded and in this case his policy caused a one-year delay. Third, the defendant did not demand, but did not waive, his right to a speedy trial. Finally, the trial court found the delay caused prejudice to the defendant. Here, the credibility of the children was of crucial importance. Frank Welch was an important witness, who interviewed the children and prepared a statement that became of even greater significance because of his death on December 22, 1987. His testimony regarding K.M. would have been exculpatory.
The children are young and have been interviewed on a number of occasions and videotaped twice. In addition, a doctor advised the district attorney of the emotional impact that the interviews and further questioning would have on K.M. The court found that the delay in the videotaping and the loss of memory and recall by the children prejudiced the defendant. The court declared that it was the responsibility of both the court and the district attorney to schedule cases and move them along to prevent delay of the type that occurred here. Accordingly, the court ordered dismissal of the charges. When all of the facts are taken together, amd are considered in accordance with the balancing test in Barker v. Wingo, the defendant’s constitutional right to a speedy trial was violated.
The findings of the trial court are supported by the record and will not be disturbed on appeal. The practice of the trial judge in postponing arraignment until all pretrial matters are concluded thwarts the purpose of section 18-1-405 and Crim.P. 48(b) and should not be followed. See Carr v. District Court, 190 Colo, at 127, 543 P.2d at 1254. The trial court’s analysis of the defendant’s constitutional right to a speedy trial is consistent with Barker v. Wingo, People v. Small, and People v. Spencer.
Accordingly, we affirm.
VOLLACK, J., dissents.