FALLS TOWNSHIP, Pa. (CBS) — A new victim has come forward in connection to a serial child rapist case in Falls Township.

According to court documents, the victim claims William Thomas showed her porn as a child and even exposed himself several times, claiming it was “natural” and “OK.”

Investigators say they recovered illustrations and writing, drawn and authored by Thomas, in which he explicitly described sexually assaulting the victim while she was prepubescent. The alleged crimes happened in the mid to late 90s at Thomas’ Pleasant Lane home and at the victims’ grandparent’s house in Yardley.

Thomas, 58, was arrested earlier this year on more than 50 child sex abuse charges. He is accused of raping at least five other young girls, and prosecutors believe there are more victims.

According to a probable cause affidavit, Thomas told police his attraction to children began at a young age and that he was aware some children were either asleep during these assaults or too young to be able to disclose abuse.

When police searched his home back in February, investigators say they found more than 1,000 pairs of little girls’ underwear hanging from the ceiling. Authorities say he kept a meticulous record of his abuse, which is why they believe his crimes date back decades.

“This man in essence was found with over 1,000 pornographic child images,” said Bucks County District Attorney Matt Weintraub last month. “He also possessed over 1,000 pairs of soiled little girls’ underwear in his trailer and these pairs of underwear were displayed throughout his mobile trailer home. This was a perverse shrine to his criminal conquests…this is a real-life boogeyman, this is your parents worst nightmare.”

The district attorney says they’ve also identified male victims and believe more charges are likely.

If convicted Thomas would face more than a lifetime behind bars.

Police are asking any other potential victims or anyone with more information to come forward to Falls Township police or county detectives. People with information can reach Falls Township Police Sgt. Christopher Clark at 215-302-3315 or at clarkpd@fallstwp.com or Bucks County Det. Lt. Robert Gorman at 215-340-8141, or at rmgorman@buckscounty.org.