Miriam Burns, 75, was murdered; her son, Billy Burns, 55, pleads not guilty by reason of insanity.

Miriam Burns, 75, died from manual strangulation and blunt force trauma, including a fractured nose and extensive bruising, according to the state pathologist. Her son, Billy Burns, 55, pleaded not guilty to murder, claiming insanity due to bipolar disorder. A defense psychiatrist said he meets criteria for a not guilty by reason of insanity verdict, but a prosecution psychiatrist testified he understood his actions at the time. The trial continues at the Central Criminal Court in Dublin.