An investigation by the Massachusetts Inspector General found that chemist Annie Dookhan was the "sole bad actor" in a scandal at the now-shuttered Hinton state drug lab — but added management failures at the lab helped Dookhan get away with faking test results.

State Inspector Genereal Glen Cunha says the lab was plagued by management failures, inadequate training and a lack of protocols.

“Other chemists in the lab repeatedly complained to superiors about Dookhan," Cunha said. "Those complaints fell on deaf ears. The supervisors in the lab told the chemists that miss Dookhan’s actions were not the chemists concerns."

But Cunha concluded that Dookhan acted alone.

"My team found no indication that any other drug lab employee was tampering with test results," he said.

Dookhan is in state prison. The lab is now closed and thousands of defendants have asked for their criminal cases to be reopened.

The ACLU and the Massachusetts Bar Association have said there's reason to doubt all the cases that came out of the Hinton state drug lab.

But Cunha's report concluded that only those cases in which Dookhan performed the primary drug tests should be treated as suspect. There are more than 40,000 of them.