A Pennsylvania man accused of killing his father and posting video of his severed head online — and calling for others to help him try to overthrow the U.S. government — is set to stand trial Monday in the Philadelphia suburbs. Justin D. Mohn, 33, faces charges of murder, abuse of a corpse, terrorism related crimes and other offenses for the 2024 killing of Michael F. Mohn at the Levittown home where they lived with the defendant's mother. Prosecutors have said Justin Mohn shot his father with a newly purchased pistol, then decapitated him with a kitchen knife and machete.