- 26 employees in the agency's hair comparison lab were allegedly involved
- Overstated forensic matches so they favored prosecutors in 80s and 90s
- Review conducted on 268 trials suggest 95 per cent were affected
- Of those impact, 32 were sentence to death - 14 have since died
The FBI and Justice Department have admitted forensic examiners from a DNA unit gave flawed evidence at nearly all United States criminal trials spanning 20 years.
It has been reported that 26 employees in the agency's microscopic hair comparison laboratory overstated forensic matches so they favored prosecutors in the 1980s and 1990s.
Research involving the National Association of Criminal Defense Lawyers (NACDL) and the Innocence Project say that 95 per cent of 268 trials reviewed had been impacted.
The FBI and Justice Department have admitted forensic examiners from a DNA unit gave flawed evidence at nearly all criminal trials spanning 20 years
The Washington Post reported that of the 200 convictions affected, 32 defendants were sentenced to death - 14 of which have since been executed or died behind bars.
Those who are still alive have been sent letters explaining the errors and how they can used further DNA testing to prove the evidence.
The mistakes do not automatically prove the convict's innocence.
Peter Neufeld, co-founder of the Innocence Project, told the Post: 'The FBIs three-decade use of microscopic hair analysis to incriminate defendants was a complete disaster.
'We need an exhaustive investigation that looks at how the FBI, state governments that relied on examiners trained by the FBI and the courts allowed this to happen and why it wasnt stopped much sooner.'
In a statement the FBI said they were committed to notifying defendants of past discrepancies and make sure 'justice is done in every instance'.
They added: '[We] are also committed to ensuring the accuracy of future hair analysis, as well as the application of all disciplines of forensic science.'
Of the 200 convictions affected by the errors, 32 defendants were sentenced to death - 14 of which have since been executed or died behind bars (file picture)
The FBI stopped its review of convictions in August 2013 after the initial troubling findings but resumed this month after at the Justice Department's orders.
A report from the department's inspector general found that the FBI and Justice Department didn't move quickly enough to identify the cases handled by 13 FBI crime lab examiners whose work was found to be flawed, meaning defendants sometimes were never notified that their convictions may have been based on bad science.
It took almost five years for the FBI to identify the more than 60 death-row defendents whose cases required further examination, and during that time at least three were executed.