BOSTON (AP) — A Massachusetts state prosecutor has resigned after revelations he received unauthorized correspondence from the chemist at the center of a state drug-testing lab scandal.

The Boston Globe reported Wednesday that the sometimes personal phone calls and emails violated protocol and may give defense attorneys grounds to argue additional cases were compromised.

Norfolk District Attorney Michael Morrissey said Wednesday he accepted the resignation of Assistant District Attorney George Papachristos. Morrissey says the prosecutor told him he did not want to be a distraction in the state's investigation of lab chemist Annie Dookhan.

Dookhan is accused of skirting protocol and falsifying results at the now-closed lab. State police have said Dookhan was involved in testing samples covering 34,000 defendants during her nine years there.