BOSTON — Faced with the daunting task of evaluating more than 34,000 drug cases handled by a Massachusetts chemist accused of misconduct, prosecutors and defense attorneys are starting with 1,140 cases of people who are already serving prison sentences based on potentially tainted evidence.

David Meier, a defense attorney and former prosecutor appointed to help sort through the legal quagmire created by the chemist's alleged actions, on Monday turned over a list of 690 people currently serving sentences in state prisons and 450 who are currently serving sentences in county jails. Samples in all of the cases were tested by chemist Annie Dookhan, who state police say failed to follow testing protocols and deliberately mishandled evidence in some cases.

Meier said it is unclear how many of those samples might have been tainted by Dookhan's actions, but said both sides want to deal first with people who are already in prison.