District Attorney Michelle Henry says Darius Hill was holding a loaded handgun and had lowered it toward the agents during the Jan. 28 raid.
The agents eventually shot the 39-year-old Hilltown Township man in the heart.
Investigators found that Hill then shot himself in the mouth.
Henry says the agents thought he was returning fire, so they fired six more shots at him.
The agents had been at the home looking for child pornography.
Hill had refused to surrender and held the gun to his chin and mouth for about 10 minutes.
