BOSTON (AP) — The chemist at the center of a scandal that shut down a state crime lab was involved in testing more than 50,000 drug samples, raising the possibility of an enormous number of legal challenges from people convicted or awaiting trial.

Lists of drug samples handled by the chemist since 2003 were turned over to public defenders and prosecutors Tuesday, five days after state police shut down the lab. Anne Goldbach, forensic services director for the state’s public defender agency, said the lists show which cases the chemist handled during her nine-year tenure at the lab.

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Gov. Deval Patrick ordered the lab closed after an investigation revealed that the chemist had not followed proper testing protocols. State police spokesman David Procopio said the investigation shows that the problems went beyond sloppiness and in some cases involved deliberately mishandling drug evidence.

Authorities have not identified the chemist, but in a letter sent to a public defender in Norfolk County, a prosecutor identified her as Annie Dookhan. She has not responded to repeated requests for comment, but her husband has said she’s being scapegoated.

State police have not fully explained how the protocol violations ended up tainting the results.

The Boston lab was involved in certifying drug samples in cases submitted by local police from around the state. It was run by the state Department of Public Health until July 1, when state police took over the operation as part of a budget directive.

Prosecutors and defense attorneys who received the lists of samples handled by Dookhan say it will be a daunting task to go through them, figure out whether evidence was mishandled and, if so, how to deal with it.

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“It’s very labor-intensive to get into our files and figure out the nature of each and every case and what the (chemist’s) involvement was,” said Cape and Islands District Attorney Michael O’Keefe, who estimates from the lists that Dookhan was involved in testing between 1,600 and 2,000 drug samples from his region.

“We’re going to try and seek some additional information and see if we can have a fuller understanding of what the actions of this individual were and then make some determinations with respect to these many, many cases should be dealt with,” O’Keefe said.

“Nothing could be more important than to get to the bottom of this and to make sure that in any cases — particularly those in which somebody was incarcerated — that they had a fair trial.”

In a statement issued last week, Dookhan’s husband said she maintains her innocence and that “more than one person was involved in botching a drug procedure.”

“We believe it’s co-workers who are trying to create a scapegoat,” he said.

State police said Dookhan resigned in March during an internal investigation by the Department of Public Health.

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Copyright 2012 The Associated Press.