NORRISTOWN, Pa. -

A Montgomery County man on trial for stabbing three members of his family is facing closing arguments Wednesday in his murder trial.

Police said Joseph McAndrew Jr. used an 18 inch dagger to kill his mother, Susan McAndrew, 64; father, Joseph McAndrew, 70; and twin brother, James McAndrew, 21 at their home in Upper Merion Township in March of 2011.

A psychiatrist has testified that McAndrew knew what he was doing at the time his parents and twin brother were killed more than three years ago.

But Dr. Timothy Michaels testified Monday in Montgomery County Court that 27-year-old Joseph McAndrew Jr. was so delusional that he didn't know his actions were wrong.

Prosecutors are seeking first-degree murder convictions in the deaths.

Prosecutors argued that McAndrew knew what he was doing when he stabbed the victims with a sword-- and knew it was wrong.

Defense attorney Paul Bauer wants a judge to find his client not guilty by reason of insanity. He says his client had stopped taking medication months before the murders.

McAndrew waived his right to a jury trial.

In exchange for that, prosecutors took the death penalty off the table.