In the largest dismissal of convictions in U.S. history, Massachusetts has thrown out more than 21,000 drug convictions linked to a former state chemist who admitted to faking test results.

Former state chemist Annie Dookhan.(Photo: David L. Ryan/AP)

The convictions were overturned by the Massachusetts Supreme Court several years after former chemist Annie Dookhan admitted to faking test results in 2013. The court threw out all drug cases where Dookhan was involved, in order to make sure that none of the individuals convicted were done so wrongly. In total, 21,587 convictions were overturned, by far the largest single dismissal of criminal charges in United States history.

According to NPR; “Over the nine years Annie Dookhan worked at the Hinton State Laboratory Institute outside Boston, she admitted to returning positive results on drug evidence she never tested and to sometimes forging co-workers’ signatures.” As the scandal unfolded, hundreds of people were released from prison and hundreds more had their charges dismissed. Dookhan herself was released from prison last April after serving about two and a half years of her three- to five-year sentence.

“Innocent persons were incarcerated,” Justice Carol S. Ball of Suffolk County Superior Court wrote in her 2013 sentencing decision. “Guilty persons have been released to further endanger the public, millions and millions of public dollars are being expended to deal with the chaos Ms. Dookhan created, and the integrity of the criminal justice system has been shaken to the core.”

But the ACLU says it’s not just a single person who is to blame. Kade Crockford of the ACLU writes that the scandal stemmed from a system that is set up to facilitate convictions. Crockford continues, “It was that system that enabled her abuse, covered it up, and then fought to preserve the convictions that stemmed from it.”

NPR’s Tovia Smith reports that on top of the 21,587 convictions tossed Thursday, prosecutors are still seeking to uphold several hundred others, which may also involve tainted evidence.