His body was found after a four-hour standoff with police who showed up at his home to arrest him.
Officials say 47-year-old Bobby Lee Moser was found dead of unknown causes in his basement when police rushed the building in Centre Township.
Court documents say Moser allegedly molested and raped a Reading girl beginning when she was 8 years old and continuing until last year, when the girl turned 16.
The standoff with state and local police began about 6:30 a.m. Wednesday.
District Attorney John Adams says Moser was fired from the Reading force in October after an investigation showed he had child pornography on his home computer.