The Clark County Sheriff’s Office on Thursday said in a press statement they had arrested James D. Mattson, 38, of Vancouver, after school staff alerted authorities of possible voyeurism. The sheriff’s office said it’s still investigating, saying the probe will be technical and time-consuming.

The charges stem from videos uncovered by investigators that were taken in female staff bathrooms at Skyview High School, according to the sheriff’s office.

The investigation began last week when Vancouver Public Schools district contacted law enforcement to report that an employee had allegedly videotaped female students in the Alki Middle School locker rooms, according to the sheriff’s office. School staff closed and secured locker rooms while the employee left the campus and refused to cooperate with investigators, the sheriff’s office said.

Detectives from the sheriff’s Major Crimes Unit searched the school and obtained a search warrant for Mattson’s residence.

“Vancouver Public Schools is aware of the arrest of a former VPS employee accused of voyeurism,” the school district told The Columbian in an email Thursday. “We continue to work closely with the Clark County Sheriff’s Office to support their investigation.”

Families have been alerted about the probe regarding Mattson, who has worked for the district since 2007 when he started as a substitute custodian, the paper reported. Currently on unpaid leave pending his termination, Mattson had also held positions including building operator for Alki and as the school’s assistant flag football coach, according to the paper.

Law enforcement was tipped off of Mattson’s alleged voyeurism after his live-in girlfriend found a video of a girl dressing in a locker room that appeared to have been recorded with a hidden camera, according to the search warrant affidavit obtained by The Columbian.

The district told KGW that Mattson had wide access to school buildings and that staff would be checking restrooms and locker rooms. Sheriff’s spokesperson Sergeant Chris Skidmore told the station that after a search warrant was served on Mattson’s home, investigators seized computers and other items.

Alki, which serves grades six through eight, is near Skyview, where Mattson is accused of making illicit recordings. Authorities say they’re still determining the extent of Mattson’s involvement and more charges could be forthcoming.

“The Sheriff’s Office Major Crimes Unit is still actively working this investigation and as investigators continue with digital forensics, additional charges from additional locations, may still be possible,” the sheriff’s office said Thursday, adding that it expects the investigation will be complex because it involves digital forensics and will require time to process the volume of evidence. Detectives are working with the school to identify victims.

First-degree voyeurism is a class C felony in Washington that can result in a prison sentence of five years in addition to having to register as a sex offender.

Mattson is lodged in the Clark County Jail. It’s not clear if he is represented by a lawyer at this time.

Newsweek has reached out to the Clark County Sheriff’s Office for comment.