Bob Salsberg

Associated Press

Annie Dookhan will begin serving her sentence immediately

At least 1%2C100 criminal cases have been dismissed or not prosecuted due to the lab%27s shutdown

Dookhan also pleaded guilty to falsely claiming she had a master%27s degree in chemistry

BOSTON (AP) — A former chemist at a Massachusetts drug lab who admitted faking test results in criminal cases pleaded guilty Friday and was sentenced to prison in a scandal that has jeopardized thousands of convictions.

Annie Dookhan changed her plea Friday in Suffolk Superior Court on charges of obstruction of justice, perjury and tampering with evidence. She was sentenced to three to five years in prison, followed by two years' probation.

The diminutive Dookhan showed no emotion during the hearing and did not address the court. She answered "guilty" and replied to a series of routine questions from the judge in a barely audible voice. She was led away in handcuffs and will begin serving her sentence immediately at the state women's prison in Framingham.

Her attorney did not comment after the hearing, and her parents left without speaking to reporters.

Dookhan sent the state's criminal justice system into a tailspin last year when state police shut down the state Department of Public Health lab she worked at after discovering the extent of her misconduct.

Prosecutors said Dookhan admitted "dry labbing," or testing only a fraction of a batch of samples, then listing them all as positive for illegal drugs, to "improve her productivity and burnish her reputation."

Since the lab closed in August 2012, at least 1,100 criminal cases have been dismissed or not prosecuted because of tainted evidence or other fallout from the lab's shutdown.

Anne Kaczmarek, the state's prosecutor, asked Judge Carol Ball to impose a five- to seven-year sentence, citing the "egregious nature" of Dookhan's actions. Ball had already said in a written memo that she would not sentence Dookhan to more than three to five years if she changed her plea.

Defense attorney Nicolas Gordon asked for a one-year sentence for his client, who was born in the Caribbean nation of Trinidad and Tobago and has no previous criminal record.

Prosecutors said Dookhan's actions had caused serious damage to the criminal justice system and cost the state millions of dollars to assess the damage and mitigate the effect on thousands of people charged with drug offenses during the nine years Dookhan worked at the lab. The court system has been flooded with motions for new trials filed by defendants in drug cases.

As of Friday, the state had spent a total of $8.5 million responding to the drug lab crisis, and another $8.6 million was authorized to be spent in the current fiscal year, according to Alex Zaroulis, spokeswoman for the state office of Administration and Finance. The Legislature has authorized as much as $30 million to cover costs incurred by the court system, prosecutors, public defenders and other state agencies.

"This ends one chapter in this situation, but the story goes on for the thousands of individuals whose lives have been affected by the conduct of Annie Dookhan," said Anthony Benedetti, chief counsel for the Committee for Public Counsel Services, the state's public defender agency. "There are millions of dollars more that will be spent and a lot of time spent by a number of people in the criminal justice system trying to deal with the fallout of what happened in that lab."

Dookhan also pleaded guilty to falsely claiming that she held a master's degree in chemistry. One of the conditions set for her probation was that she not use the false credentials when seeking employment after serving her sentence. She was also ordered to have mental health evaluations after leaving prison.