Federal prosecutors say a 35-year-old registered sex offender hacked into more than two dozen Snapchat accounts of minor victims in an effort to gather sexually explicit images and videos last year.

Barton George Scott, whose city of residence is not known, appeared in federal court for the first time Tuesday on charges revealed a newly unsealed 26-count indictment outlining child pornography and computer hacking charges.

According to the U.S. Attorney’s Office, George allegedly hacked into the social media accounts between April 30 and August 8, 2017, at times using “extortionate tactics” to try to gather the explicit files.

Messages were left seeking comment from an attorney for Scott, who according to the indictment is required by Wisconsin law to register as a sex offender. His charges now include committing a felony while registered as a sex offender.

The indictment, which was returned under seal earlier this month, accuses Scott of producing child pornography of a known minor and six counts of attempted production of child pornography involving other minors last year. Authorities seized six cellphones and an iPad from George during the investigation, according to charges.

Scott was scheduled to return to court Thursday afternoon for a detention hearing and arraignment. He is being held in federal custody on the charges in Sherburne County.

The FBI investigated the case alongside the Carver County Sheriff’s Office, the Stillwater Police Department, the Washington County Sheriff’s Office, the St. Croix County Sheriff’s Office, New Richmond Police Department, and the Anne Arundel County Sheriff’s Office.

Law enforcement also believes there may be additional victims and the FBI is asking anyone with information to call (763) 569-8000. Callers can remain anonymous, authorities said.