A former substitute janitor for the Oak Harbor School District was arrested earlier this month for possessing child pornography, according to court documents.

Prosecutors charged 42-year-old Clinton E. Shell in Island County Superior Court March 8 with four counts of first-degree possession of depictions of minors engaged in sexually explicit conduct.

Oak Harbor schools Superintendent Rick Schulte said Shell only worked for five days over the 2012 Christmas vacation, so he had no interaction with students. Shell’s name was taken off the substitute list and he will no longer be able to work for the district.

“Our involvement with him was very short and limited,” he said.

Schulte said the district did a background check on Shell before he was hired, but found he didn’t have a criminal record.

Still, investigators were alarmed that someone with an interest in child porn would take a job at a school district, court documents indicate.

Shell was first identified as a suspect in a 2006 Immigration and Custom Enforcement investigation targeting child pornography users and distributers, according to a report by Detective Ed Wallace with the Island County Sheriff’s Office.

Agents from the FBI and the Naval Criminal Investigative Service contacted Shell at his Oak Harbor home in January of 2011. The agents found “thousands of images of child erotica on his laptop computer and multiple child pornography videos on a thumb drive,” the report states.

The agents sent seven video files to the National Center for Missing and Exploited Children, where they were identified as a known pornography series with identified victims.

In January of this year, an NCIS agent interviewed Shell. He said he had been “staying clean” since the agents came to his home in 2011, but admitted that he had watched child porn videos since then, Wallace wrote.