Joel Davis was making a name for himself as an ardent advocate for victims of sexual violence. The 22-year-old Columbia University student founded an international group called Youth to End Sexual Violence—and served as a United Nations youth ambassador, attending notable events and penning published essays on his advocacy work. According to one local outlet, he was even nominated for a Nobel Peace Prize.

But his do-gooder reputation came crumbling down this week, when federal prosecutors arrested and charged Davis with sex crimes against children, accusing him of possessing child pornography and attempting to have sex with a minor.

“Joel Davis started an organization devoted to stopping sexual violence, while allegedly engaged in the duplicitous behavior of sharing explicit images of infants engaged in sexual activity,” U.S. Attorney Geoffrey S. Berman said in a statement released Tuesday.

The news shocked his former peers at American University, a school he briefly attended.

But one American University graduate told The Daily Beast that Davis “was more interested in the celebrity than in the work” required of his causes.

“There was one time I was assisting other students in putting on an event to raise money for girls’ education in the developing world, and I guess they'd heard about his work, so they reached out to him,” the former student, who asked to remain anonymous, said. “But the partnership ended up falling apart over issues related to how much of the spotlight he would have to himself.”

A Facebook post from April on the Youth to End Sexual Violence account features a headshot of Davis and encourages users to attend his Columbia University Ted Talk on the “role of trust in ending sexual violence.” Footage of the talk was removed following his federal charges.

A Columbia University spokesperson told The Daily Beast the allegations against Davis are “unfathomable and deeply disturbing.”

According to a criminal complaint filed in the Southern District of New York, Davis texted with an undercover FBI agent, whom he believed to be the father of a 9-year-old girl, describing “explicit sexual activity that he intended to engage in” with the girl. He also allegedly described sexual encounters with the “purported” 2-year-old daughter of the undercover’s girlfriend.

Davis told the undercover he was into children ages zero and up with “no limits,” and that he had had sexual encounters with a nine-month old boy, a six-year-old girl, and a seven-year-old boy, according to the Department of Justice.

Law enforcement searched Davis’ phone after obtaining a search warrant. He allegedly admitted to sending the illicit text messages and to having a sexual encounter with a 13-year-old he met on Grindr in June, according to the Department of Justice.

The lauded activist, who once worked alongside Angelina Jolie at a United Nations event, faces up to at least 10 years in prison for enticement of a minor to engage in sexual activity, at least 15 years in prison for attempted sexual exploitation, and at least five years in prison for owning child pornography, if found guilty.

Davis told officials he “wants to think he would not have shown up” to meet the father and girls offline, but “he may have” if he were confident that the user was not law enforcement, according to the criminal complaint.

In columns for The Columbia Spectator, Davis wrote about being sexually abused as a child, and the trauma he’s experienced since: “I started popping caffeine pills like Tic Tacs, thinking that if I could stay completely awake I wouldn't have to suffer through the subconscious film reel of my rapes.”

There is no direct relationship between surviving sexual assault in youth and becoming an abuser in adulthood, according to Dr. Elizabeth J. Letourneau, director at the John Hopkins Moore Center for the Prevention of Child Sexual Abuse.

“Something else needs to have happened between the original victimization as a child and then engaging in harmful sexual behaviors as an adult. For example, the development of atypical or deviant sexual fantasies is a crucial component for that relationship to exist in adults,” the John Hopkins doctor said.

“Most individuals who are sexually assaulted do not go on to engage in harmful sexual behavior or the use of child pornography,” Letourneau added.

Davis, who did not respond to requests for comment, once wrote he was “struggling to repair my relationship to my body—a seemingly impossible feat when you’re introduced to sex through violence.”