INDIANAPOLIS — An Indianapolis man with a history of sex crimes against children will now serve federal prison time after he pleaded guilty to sending child sexual abuse material.

On Tuesday, the United States Attorney’s Office for the Southern District of Indiana said Willam Cass has been sentenced to 15 years in federal prison after pleading guilty to distribution and receipt of child pornography. The sentencing comes after an investigation into CyberTips from the National Center for Missing and Exploited Children.

In the tips, Google reported that a user sent suspected child sexual abuse material while using Google Hangouts. This is a now-discontinued instant messaging service. Court documents show that the account in the tips is linked back to Cass.

Cass’ history of sex crimes against children includes sexual misconduct with a minor and child molesting convictions in Hancock County. He was also convicted of vicarious sexual gratification in Marion County.

While investigating his online activity, court documents show several searches for inappropriate images of little girls along with “legal age of consent in Indiana.” In his Google Photos, the document said investigators found photos of young girls, some of which were indecent.

The documents also show a conversation with another user where Cass claimed to have paid a girl that he met at the pool for sexually explicit conduct. Later when the other user asked if he was busy, he responded “I’m with the little girl right now.”

The documents also show that he told the other user that he was seeking other children to sexually abuse. He told the other user that he wanted their help getting 8 to 10-year-old girls for sexual purposes. Later, when the user asked Cass if he was going to work, he replied that he was going out to find another little girl.

During the conversation, the document says there was a short discussion of Cass providing the other user money in exchange for pictures before sending a photo of child sexual abuse material.

As part of the sentence, Cass was ordered to be supervised by the U.S. Probation Office for life following his release from federal prison and pay $5,000 in restitution to the child exploitation victim. Cass must also register as a sex offender wherever he lives, works or goes to school, as required by law.