BOSTON (AP) -- The chemist at the center of a scandal that has shut down a Massachusetts 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 in drug cases.

Anne Goldbach, forensic services director for the state's public defender agency, says public defenders and prosecutors on Tuesday were given lists of drug samples handled by the chemist since 2003. State police shut down the lab last week.

The lists show the chemist was involved in testing more than 50,000 samples at the lab.

Gov. Deval Patrick ordered the lab closed after an investigation revealed that the chemist had not followed proper testing protocols.