An Upper Darby man with a history of violent crimes was arrested today for the murder of 84-year-old Jane Morgan.

William "Billy" Williams, who lived in the same apartment complex as the victim, was charged with murder, aggravated assault, rape, burglary and other crimes.

Michael Chitwood, Upper Darby superintendent of police, said Williams was on authorities' "radar screen" early in the investigation. DNA evidence taken from Morgan and compared to that of Williams was the "slam dunk" police needed for the arrest, he said.

When Jane Morgan's body was discovered on Sept. 9, investigators first thought she might have died of natural causes. Morgan, known for her affection for her cats, was lying in her bed with a pillow and bathrobe.

An investigation revealed that she had died after a struggle and that she was a victim of a sexual assault.

Contact staff writer Mari A. Schaefer at 610-892-9149 or mschaefer@phillynews.com.