The wrongful conviction of Toshikazu Sugaya for the 1990 murder of a 4-year-old girl in Tochigi Prefecture was the result of prosecutors’ failure to follow the basic rules of an investigation, the Supreme Public Prosecutor’s Office admitted Thursday.
Despite the lack of sufficient understanding or analysis of the initial DNA test, the prosecutors placed too much confidence in the scientific evidence, on top of failing to realize that Sugaya’s confession, including later updates, was false, the top prosecutor’s office said in a 25-page report.
“Needless to say, the mission of prosecutors is to conduct investigations and trials that are faithful to the basics, and gather evidence and testimony that is necessary to investigate the truth of a crime, indict a person who must be indicted and demand a just punishment,” the report states. “We must never punish an innocent person, thus it is very regrettable that we have invited this grave incident.”
Sugaya, 63, was acquitted March 26 by the Utsunomiya District Court in a retrial that struck down his life sentence over the murder of Mami Matsuda in the city of Ashikaga. Sugaya spent more than 17 years behind bars before he was released June 4. No other arrest was made in the slaying.
The office said it formed an eight-member in-house review team for Sugaya’s case the day he was released. The team went through all the related documents and interviewed the prosecutors who were involved in the case to compile the report.
To prevent similar mistakes, the office said prosecutors, through retraining sessions, must improve their interrogation skills and their ability to assess the personality traits of suspects.
The office added it will establish a system that will put a greater burden on senior district prosecutors to take the lead in serious cases and improve communications among prosecutors and between prosecutors and police.
The report reveals how prosecutors brushed aside the lack of evidence to support Sugaya’s confession, which past reports said came after marathon interrogations. Previous reports alleged Sugaya was pressured to confess.
According to the report, the lead prosecutor, who wasn’t identified, didn’t talk to two witnesses who saw a man walking with the victim, despite Sugaya confessing that he rode his bicycle with her as a passenger. The girl’s fingerprints were not found on his bike.
In addition, the prosecutor found no evidence proving Sugaya was a pedophile. The footprints along the riverbank where the corpse was found did not match any of Sugaya’s shoes, but Sugaya said in one version of his confession that his mother threw away the pair he had been wearing. In a further sign of inconsistency in this admission, his mother said she had never thrown away any of his shoes, the report says.
Despite the lack of corroborating evidence, the prosecutor concluded that Sugaya’s confession, in its entirity, contained information that could only come from the culprit, the report says.
“In hindsight, although there was the DNA test, we should have looked into the (supposed) evidence that contradicted the facts,” said Kazuhiro Suzuki, head of the criminal division of the Supreme Public Prosecutor’s Office. “It is necessary to (realize) that even someone who is innocent (might) confess to a crime he didn’t commit, and (to examine) the mechanism of why that happens.”
The senior official also said the prosecutors should not have told Sugaya during interrogations that DNA tests on his sperm matched what was found on the victim’s underwear.
The report goes into great length analyzing how the prosecutors misused the forensic evidence.
According to the report, although the lead prosecutor, unnamed, in the first trial was told by the police and the National Research Institute of Police Science about the nature of DNA tests, he did not have a full understanding that this was only a matter of probability and thus should only have been considered only as a reference point.
“Although a DNA test sample is evidence that should be used comprehensively with other evidence, including confessions, because Mr. Sugaya had confessed to a crime that was subject to a harsh penalty, we must admit that the prosecutor overrated the result of the DNA test and evaluated this as evidence that confirmed (guilt),” the report says.
The DNA test, which used a method called MCT118, was performed by a specialist at the National Research Institute of Police Science. But because the negatives of the scanned sample used for analyzing the accuracy of the performed test were lost by the time of the retrial, it is impossible to determine if the DNA test was accurate, the report says.
The reason for the loss of the negatives and data is unknown, the prosecutor’s office said, but prosecutors were also at fault for failing to demand that the institute keep the negatives and data from the test sample, the report says. It adds the lead prosecutor failed to closely analyze Sugaya’s confession, including updated versions after further interrogations.
Sugaya had signed a confession for the police during a 13-hour interrogation, but when the prosecutor brought him to the court for a preliminary arraignment, he told the judge he “did not want to answer the question” when asked if he had committed the crime.
The report says the prosecutor missed the opportunity to look into why Sugaya did not plead guilty at this time after telling police during the interrogation he killed the girl.
At the retrial that began in October after fresh DNA analysis failed to match the sperm sample, thus proving Sugaya’s innocence, the court ruled he was unable to withstand the pressure of the harsh interrogations and made the false confession after he was confronted by the initial DNA result.
The court admitted the confession lacked credibility and was false, noting the initial DNA test was not conducted in a scientifically reliable manner and should not have been admissible as evidence.
The court also said the questioning was illegal as the prosecutor did not tell Sugaya he had the right to remain silent.