A defense psychiatrist says 26-year-old Maurice Milbourne heard voices and believed he would be "burned" if he didn't kill his 79-year-old grandmother, Gladys Milbourne, in July 2007.
Defense attorney Francis Holloran told a judge Milbourne has been mentally ill for a long time and should be committed to a mental health facility.
The Delaware County Daily Times reports prosecutors said on Friday that Milbourne knew right from wrong at the time of the killing inside the Chester apartment. Assistant District Attorney Michael Dugan said Milbourne changed clothes in a bid to not be caught.
Judge Ann Osborne says she'll rule on the defense request later this month.
Information from: Delaware County Daily Times