BOSTON — A former chemist at a Massachusetts drug lab convicted of stealing drugs to feed her addictions may have tainted as many as 10,000 criminal prosecutions, not just a few dozen as first thought, according to newly released court documents.

Now, defense lawyers are calling for an independent review of the cases, according to The Boston Globe.

Sonja Farak was addicted to cocaine, methamphetamine, and amphetamines, but between 2004 and 2013 never left her Amherst office to buy street drugs, according to the records.

“She obtains the drugs from her job at the state drug lab, by taking portions of samples that have come in to be tested,” one of Farak’s therapists wrote after an April 2009 counseling session, according to records filed in Hampden Superior Court.

Randolph Gioia, deputy chief counsel for the Committee on Public Counsel Services, the state’s public defender agency, called for an “independent, completely transparent investigation” into the thousands of people potentially affected by Farak’s actions.

“What we are dealing with is thousands of alleged drug samples at the Amherst lab that were analyzed for use in court by someone who has admitted to widespread tampering of the samples,” he said, adding that she was also under the influence of drugs while at work.

Farak pleaded guilty in 2014 to four counts of tampering with evidence, four counts of stealing cocaine from the lab, and two counts of unlawful possession of cocaine, and was sentenced to 18 months in prison. She has since been released.

The office of current Attorney General Maura Healey is looking into the matter.

“Our office has volunteered to lead the Commonwealth’s investigation into the timing and scope of Sonja Farak’s misconduct to explore how many cases could be potentially affected,” Healey spokesman Christopher Loh said.