PORTLAND, Ore. (KOIN) — A man accused of 137 voyeurism counts for allegedly putting hidden cameras in a girl’s locker room at a middle school and a female staff bathroom at a high school in Vancouver entered a guilty plea during a court appearance on Friday.

Thirty-eight-year-old James Mattson, a former custodian at Alki Middle School, is accused of putting hidden cameras in the girl’s locker rooms of Alki and the female staff bathroom at Skyview High School. The videos authorities found date back to 2013, officials said.

Despite Mattson’s submitted pleas, the Clark County Sheriff’s Office says not much has changed from their perspective.

“From our perspective at the Sheriff’s Office, there is still investigative work to be done and they are going to continue working through that; both combing through some of the digital forensic evidence that they have and then working to identify victims,” Sgt. Chris Skidmore of CCSO said.

But how victims will be identified and notified remains a major question for staff and parents alike.

“Our intent is certainly not to re-victimize or bring people through this trauma. And they’ll do it in such a way that any images are completely sanitized … and that would be handled by an absolute minimum number of people as possible,” Sgt. Skidmore said.

In a video message to parents, the Vancouver Public Schools superintendent said law enforcement requested the district’s assistance in helping to identify victims using facial images. That identification process has not yet begun.

KOIN 6 News asked the district on Friday for their response to Mattson’s court appearance. A spokesperson issued a statement explaining in part, “we are in the process of consulting with the Clark County Sheriff’s Office to determine what the appropriate next steps will be. We will continue to support our students and staff with counseling resources and other services.”

Officials said pending the investigation, more charges may come.

Authorities and Vancouver Public Schools have searched both schools and found no active hidden cameras. Meanwhile, the district says they are continuing periodic searches of restrooms and locker room spaces and are reviewing potential prevention methods for the future.

Mattson’s guilty plea comes after his Oct. 12 arrest when he was booked into Clark County Jail on the 137 first-degree voyeurism charges.

A search warrant obtained by KOIN 6 shows Mattson’s live-in girlfriend was the first to report the tapes.

According to her, after Mattison left for work as the custodian at Alki Middle School, she walked by the computer room and noticed his computer was open. After going through his files, she “found a video that was clearly an underage child getting dressed in a locker room. The child was in their underpants and bra and was putting on pants. The video appeared to be on a hidden camera.”

Mattson’s next court appearance is set for Dec. 20 for a pre-sentencing hearing. During Friday’s court appearance, the judge said Mattson may still have to go to trial because of aggravating factors.