QUINCY — The man suspected of killing a Massachusetts police officer, as well as an innocent bystander, is being held without bail. Emanuel Lopes, 20, has been arraigned Tuesday for two counts of murder.

Authorities say Lopes struck Weymouth Officer Michael Chesna with a rock Sunday morning, grabbed the officer's service weapon and shot him 10 times. Chesna was investigating reports of an erratic driver and car crash.

Authorities say Lopes then shot 77-year-old widow Vera Adams through the sliding glass door of her home. Lopes was later shot in the leg by police.

Lopes' lawyer argues he is not mentally competent to stand trial. Lopes' mother in an affidavit seeking a restraining order on her son said she was "afraid" of him because of mental health and substance abuse issues.