It's a tragic end to a sad, bizarre tale.

Warren Pennick, 56, the Lansdale man convicted to 20 to 40 years in prison earlier this year for stabbing his mother to death in their Perkiomen Avenue home on Halloween 2012, was found dead in his prison cell at The State Correctional Institution at Camp Hill early Tuesday morning, according to the Associated Press.

Pennick's death is the second one at the prison in a month. He was found unresponsive shortly after 4 a.m. Tuesday. An autopsy will be performed to determine cause of death, per the report.

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Pennick was found guilty but mentally ill of third-degree murder in January in Montgomery County Court of Common Pleas for stabbing his mother Lorraine, 79, to death. 

She was found with her throat slit at the bottom of their basement stairs in the home they shared. A 7-inch knife was on her chest. Bloody clothes were found in Pennick's bedroom.

Pennick told police he killed his mother out of mercy because he feared they would soon be broke and homeless, as they could not afford to pay repair bills.

According to an affidavit, on Oct. 31, 2012 at 10:12 a.m., Pennick walked into the lobby of Lansdale Police Department and talked to dispatcher Jason Platt. 

Dispatcher: Yes, how can I help you?

Pennick: I just killed my mother.

D: ... Say again.

P: I just killed my mother

D: What? Where? Where at?

P: 635 Salford Avenue

Lansdale Officer James Owens and Detective Sgt. Mike Trail interviewed Pennick, who told them he stabbed and pushed his mother down the stairs. Owens would later find Lorraine Pennick lying in a pool of blood. 

Blood would be found on Pennick's wristwatch and sneaker while at the police station. More blood was found on the hot water faucet in the basement, and next to the sink was a bloody paper towel.