(CNN) -- A former Massachusetts state chemist arrested for allegedly lying about drug evidence pleaded not guilty Thursday, as prosecutors continued to review more than 1,000 cases in which people went to prison because of the chemist's work.
Annie Dookhan, 35, pleaded not guilty to 15 charges -- eight counts of evidence tampering, five counts of witness intimidation, one count of perjury, and one count of making a false claim of holding a master's degree, according to Maura A. Hennigan, clerk magistrate of Suffolk Superior Criminal Court.
When Dookhan was arrested in September, Massachusetts authorities said they would review the sentences of 1,140 people who were in prison after being convicted with evidence at least partly provided by Dookhan.
"It is going to be a very, very long process," Renee Algarin, deputy press secretary for the Suffolk County district attorney, said Thursday. Each district attorney's office in the state is handling its own cases, Algarin said.
According to state officials, Dookhan worked for nine years with the Department of Public Health.
Among the charges she faces is an allegation that she misled her employers when applying for the job and lied when said she had a master's degree in chemistry from the University of Massachusetts.
Dookhan pleaded not guilty to that charge on Thursday.
Dookhan is expected to be in court again on February 13, 2013, for a pretrial conference.
At the request of Dookhan's attorney, a magistrate Thursday approved moving her nightly curfew time while she awaits trial to 10 p.m., from the previously ordered 6 p.m. She is being monitored by a GPS ankle bracelet.
Calls by CNN to Dookhan's attorney were not immediately returned.
CNN's Brittany Brady contributed to this report.