The Justice Department and FBI have reportedly acknowledged that nearly every examiner in the FBI Laboratory’s microscopic hair comparison unit gave flawed testimony in almost all trials where they offered evidence against criminal defendants over more than 20-year period before 2000.

The Washington Post, citing information from the National Association of Criminal Defense Lawyers and the Innocence Project, reports 26 of the 28 examiners overstated forensic matches in favor of prosecutors more than 95 percent of the 265 trials that were reviewed.

The newspaper reports the organizations are assisting the government with the post-conviction review of questioned forensic evidence and provided the statistics under an agreement with the government to release results after the review of the first 200 convictions.

The cases include those of 32 defendants sentenced to death; of those, 14 have been executed or died in prison, the Post reported in a story posted on its website.

The FBI errors alone do not mean there was not other evidence of a convict's guilt, the Post said. Defendants and federal and state prosecutors in 46 states and the District of Columbia are being notified to determine whether there are grounds for appeals, according to the newspaper. Four defendants were previously exonerated.

In a statement released to the Post, the FBI and Justice Department vowed to continue to devote resources to address all cases and said they "are committed to ensuring that affected defendants are notified of past errors and that justice is done in every instance. The department and the FBI are also committed to ensuring the accuracy of future hair analysis, as well as the application of all disciplines of forensic science."

The FBI is waiting to complete all reviews to assess causes but has acknowledged that hair examiners until 2012 lacked written standards defining scientifically appropriate and erroneous ways to explain results in court, the Post reported. The bureau expects this year to complete similar standards for testimony and lab reports for 19 forensic disciplines, the newspaper said.

Federal authorities launched the investigation in 2012 after the Post reported that flawed forensic hair matches might have led to the convictions of hundreds of potentially innocent people since at least the 1970s, typically for murder, rape and other violent crimes nationwide.

The review confirmed that FBI experts systematically, testified to the near-certainty of “matches” of crime-scene hairs to defendants, backing their claims by citing misleading statistics drawn from their case work. In reality, according to the newspaper, there is no accepted research on how often hair from different people may appear the same. Since 2000, the lab has used visual hair comparison to rule out someone as a possible source of hair or in combination with more accurate DNA testing.

The Associated Press contributed to this report