FALLS TOWNSHIP, Pa. (CBS) — A 58-year-old Bucks County man is facing what prosecutors say would be more than a lifetime behind bars on several charges, including five counts of rape of a child. But prosecutors say they believe there are more victims.

The break in the case, says Bucks County District atty Matt Weintraub, came when a contractor found a piece of plywood in a trailer home in the Midway Village Trailer Park in Morrisville. On that plywood, a hand written description of an assault of two girls ages 3 and 6-and-a-half or 7.

It was connected back to William Thomas who had done work on the trailer in the past.

When police searched his home, Weintraub says they found more than 1,000 pairs of little girls’ underwear hanging from the ceiling.

“He also possessed over 1,000 pairs of soiled little girls’ underwear in his trailer, and these pairs were displayed almost throughout his mobile trailer home,” Weintraub said at a press conference. “This was a perverse shrine to his criminal conquests.”

“The human race hasn’t come up with words to describe what we saw in that trailer. This is a parent’s worst nightmare,” said Lt. Henry Ward of the Falls Township Police Department.

Weintraub says there are six victims they are aware of, ages 2 to 10, but the so-called trophies indicate there could be many more, dating back 40 years.

Thomas is a lifelong resident of Levittown. He grew up on Pleasant Lane near the Midway village trailer park, then around 2006, he moved into a mobile home.

Thomas worked as a handyman. Investigators say he indicated he would steal the underwear when he did work in homes, and then would stalk the victims.

Police are also investigating reports of similar occurrences at Thomas’ previous addresses, including a home on Pleasant Lane and the Pennsbury Woods apartment complex on New Falls Road in Levittown.

In his most recent home, a trailer on Bristol Pike, investigators discovered children’s toys, dolls placed in sexual positions, and a handwritten note outlining that the rules of the room involved all kids being naked.

They also found drug paraphernalia, which tested positive for methamphetamine and marijuana.

“I think it’s horrible. It’s disgusting. I hate when people do things like this to children. It makes me sick,” said Jessica Chobert, who lives at the trailer park.

Chobert does not have children, but says Thomas had done work in her unit before.

“I thought he was nice,” she said.

Thomas also ran a business called Thomas Construction, which authorities believe allowed him to access to hundreds of homes and enabled him to identify and abuse his victims.

The investigation by Bucks County authorities and Falls Township police began in November, after a Good Samaritan at the trailer park found a piece of plywood in a vacant unit that Thomas had been renovating.

It detailed the explicit sexual assault of two victims, one just 2 years old at the time. According to the writing on the wood, this encounter happened early Christmas morning in 2014 when a neighbor asked Thomas to watch his young daughters while he went to the store to buy tape to wrap Christmas gifts.

This was just one of Thomas’ many alleged crimes. Authorities say he kept a meticulous record of his abuse, which is why they believe his crimes date back decades.

“This man was a trophy collector and creator of monumental proportion. He was a historian. He historically recorded all of his conquests,” Weintraub said.

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.

“I fear we may never know the scope of this man’s predation,” Weintraub said.

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

Weintraub says Thomas, if convicted, would face more than a lifetime behind bars, but they’re asking any other potential victims or anyone with more information to come forward to Falls Township police or county detectives.

He says in addition to the photos, they have VHS tapes, but haven’t reviewed them, and they also confiscated computers from the home that also need to be reviewed.

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.

If you have concerns about child abuse or questions, please call Network of Victim Assistance’s 24-Hour Victim Support Hotline at 1-800-675-6900.