A Rochester man has been charged with felony sex crimes after an investigation by police found he has coerced scores of child victims into sending him sexually explicit photos and videos.

John Timmerman, 43, was arrested Tuesday in what Rochester police say is the department's largest-ever cyber investigation into child sexual abuse material. He faces 13 counts related to using electronic communication to engage in child pornography.

Investigators say Timmerman would create Facebook and Instagram accounts pretending to be minors to lure in his victims. He would then solicit many of the victims to produce or distribute child sexual abuse material.

Rochester police say their investigation identified 169 victims aged 8-17 from throughout the U.S., as well as in Canada, the U.K. and Nigeria. Investigators expect to identify additional victims as they continue to work through the evidence in the case.

"Sex crimes cases like this are extremely complex and incredibly horrendous, and unfortunately, we are seeing an increase in them," Rochester Police Chief Jim Franklin said in a statement.

According to the criminal complaint:

Rochester police received a tip in October related to the solicitation of minors to produce child sexual abuse material. They later discovered the tip matched others from 2022 and 2023 related to the same suspect.

In November, investigators were granted a search warrant for Timmerman's devices, where they found social media accounts that appeared to have been created to impersonate minors.

Further investigation found that going back as far as 2021, Timmerman used those accounts to start communication with his victims. The conversations included asking them about their sexual history and encouraging them to send photos and videos of themselves naked. In some cases, he would direct the victims, both male and female, to perform a sex act on themselves.

When the victims did not comply with further requests, Timmerman would threaten to send the photos and videos to family and friends. Even as some of the victims begged him not share their photos, even threatening to take their own lives, Timmerman would continue to threaten the victims.

Timmerman made his first appearance in court on Thursday, where the judge set his bond at $750,000 unconditional, or $150,000 with conditions, including that he does not use the internet or have unsupervised time with children.

Rochester police were assisted by the Olmsted County Sheriff's Office, Minnesota Bureau of Criminal Apprehension and FBI in its investigation, which the department says remains ongoing.