Misconduct in DNA Profiling: Incident Disgraces Trust in Forensic Science

Editorial

14:29 JST, September 21, 2025

An unprecedented incident that undermines public confidence in forensic science has occurred. DNA profiling serves as critical evidence in investigations and trials. Fraud is absolutely unacceptable.

A male technical staff member employed at the science research institute of the Saga prefectural police repeatedly engaged in misconduct while doing work in DNA profiling. The prefectural police applied disciplinary action and dismissed the staffer and sent papers pertaining to the case to prosecutors on suspicion of creating false official documents with a seal, among other charges.

The staffer reportedly handled 632 DNA profiling cases to date, committing fraud in 130 of them between June 2017 and October 2024.

He pretended to have conducted some cases of DNA profiling that were never performed. In other cases, he lost pieces of gauze containing a sample after profiling and covered it up by substituting new pieces of gauze.

The misconduct was discovered last October when his supervisor noticed discrepancies in some documentation. The staffer reportedly explained, “I thought finishing the profiling quickly would improve my evaluation.”

The staffer conducted the analyses alone, and his supervisor’s oversight was inadequate. The fact that such misconduct went unnoticed for over seven years is a serious matter.

It must be said that the system itself for conducting profiling was problematic, beyond the individual attributes. The prefectural police said they will implement measures to prevent a recurrence, such as having supervisors be present during the work.

Nationwide, police conducted 253,900 cases of DNA profiling in 2024, more than 20 times the number from 20 years prior. It is used in investigations spanning a wide range of crimes including murder, robbery and theft.

DNA profiles registered in a database are also proving effective in investigating unsolved cases and additional offenses.

There has been a growing emphasis in recent years on objective evidence, reflecting a shift from an over-reliance on confessions. The shock that fraud is occurring in DNA profiling, a cornerstone of this approach, is profound.

In the so-called Ashikaga murder case in which the defendant was acquitted in a retrial in 2010, DNA analysis from an era of lower precision contributed to a false conviction. Without ensuring the reliability of such analyses, the criminal justice system cannot function.

The Saga prefectural police deny that the staffer’s misconduct affected investigations. They said that 16 cases of the falsified analyses were submitted as evidence to prosecutors, but they were not used in determining decisions or in court trials.

Can this explanation be accepted on its own? If samples are not stored properly, fresh profiling would become impossible when reinvestigations are needed. Verification, including by third parties, is necessary to determine if there truly was no impact.

Similar misconduct could be occurring at police organizations other than the Saga prefectural police. The police must take this incident seriously and urgently improve guidance for technical staffers conducting DNA profiling and establish systems to prevent misconduct.

(From The Yomiuri Shimbun, Sept. 21, 2025)