An Oregon high school custodian was arrested Wednesday after authorities found more than 7,000 photos of abused children between the ages of four to 12 in his possession. According to local reports, Mitchell J. Grandlund, 34, of Madison High School was also found with methamphetamine during his arrest and had several pairs of children's underwear in his car trunk, according to a probable cause affidavit.

Portland police and the FBI said they discovered child porn on his Google Photos account. Police were able to identify him as his uploads included pictures of himself, his ID and his resume. Police obtained the search warrant on March 30, the Oregonian reported Thursday.

Police launched an investigation after receiving 15 separate tip-offs since the beginning of the year about his activities and discovered thousands of photos, the affidavit said. Grandlund told investigators he would look at the images when he "fantasizes about having sexual contact with children," the affidavit read. Grandlund also admitted to using meth "for a while," and that he smoked the drug every day.

According to the Oregonian, no children from Madison High School were identified as victims.

Grandlund was held in the Multnomah County Detention Center on Thursday on suspicion of first- and second-degree encouraging child sexual abuse and unlawful possession of methamphetamine.

Court records showed Grandlund was convicted in Oregon in 2008 for failing to appear in court. He also had a 2006 conviction in Texas for failing to identify himself to authorities and a drug-related conviction as well as a criminal mischief conviction in Utah in 2011 and 2012 respectively.

As the investigation in the case continues, Portland police urged anyone with more information about Grandlund to come forward.

This article originally appeared in IBTimes US.