Shock (1946)

Dr. Cross, a psychiatrist, is treating a young woman, Janet Stewart, who is in a catatonic state, brought on when she heard loud arguing, went to her window and saw a man strike his wife with a candlestick and kill her. As she comes out of her shock, she recognizes Dr. Cross as the killer. He takes her to his sanitarium and is urged by his nurse/lover, Elaine Jordan, to give Janet an overdose of insulin. Can he bring himself to murder Janet in cold blood?