Annie Dookhan, the former Massachusetts drug lab chemist who admitted to faking drug sample results, forging signatures and skipping proper procedures was arrested on Sept. 28. Dookhan faces two counts of obstruction of justice and one count of falsely pretending to hold a degree from a college or university.

Attorney General Martha Coakley said more charges could follow: “She’s only facing three counts today relating to two particular cases. And if you think of the scope of time and the number of cases, we do expect this to be an ongoing investigation. This is not the end of the charging."

The arrest comes as special courts are being established to handle the onslaught of criminal cases that could be reopened because of Dookhan’s actions. So far, authorities have found more 1,100 inmates who are in prison based on evidence analyzed by Dookhan. Judges have freed, reduced the bail or suspended the sentences of at least 20 defendants.

Dookhan previously admitted to investigators that she faked test results on drug samples and took other shortcuts.

Coakley didn’t identify a motive but implied Dookhan wasn’t stealing the drugs or using them herself. “We certainly do not have, as we’ve seen in other cases, someone who had a drug habit or someone who was looking for a monetary gain. We do not have that evidence in this case,” she said.

Dookhan resigned from her job in March 2012 after she was found forging a coworker's initials on lab paperwork. According to the State Police reports, Dookhan has admitted guilt, telling investigators, “I messed up bad. I don’t want the lab to get in trouble.”