P' was picked up by a gang of robbers in a car from the street. He was given a revolver and asked to shoot at 'M'. When 'P' resisted, a revolver was put on his ear and he was told that if he did not shoot, he would be shot dead. Then 'P' shot 'M' dead. On a charge of murder, 'P' argued that his act was not voluntary nor was there mens rea. 'P' is guilty of: