For a 22-year-old Columbia University student, Joel Davis had built an impressive reputation as an activist for ending sexual violence.

He was the founding executive director of the international organization Youth to End Sexual Violence. He served as a youth ambassador for the United Nations Special Representative on Sexual Violence in Conflict. He was on the steering committee of the International Campaign to Stop Rape & Gender Violence in Conflict, a group of more than 5,000 human rights organizations and experts worldwide.

Davis traveled around the world, worked alongside high-profile activists like Angelina Jolie, delivered a TED talk and appeared on media panels. In 2015, at the age of 19, he claimed to have been nominated for a Nobel Peace Prize.

His work focused particularly on ending sexual violence against the most vulnerable victims – children.

Yet behind this virtuous front, Davis was allegedly committing the same types of crimes he claimed to be fighting, federal prosecutors now say. On Tuesday, authorities arrested Davis on charges of attempting to sexually exploit a child, enticing a child to engage in sexual activity and possessing child pornography. If convicted, he could face a long sentence.

No plea has been entered for him and he did not respond to messages from The Washington Post.

Over the course of several weeks between May and late June, prosecutors say, Davis exchanged text messages with undercover FBI agents, trying to arrange meetings with a 9-year-old girl, an 8-year-old girl and a 2-year-old boy. Davis allegedly sent the undercover agents sexually explicit photos and videos of children as young as infants, and made clear that he wanted to have sex with children of any age, according to a federal criminal complaint.

He also admitted to meeting a 13-year-old boy on the dating app Grindr, speaking with him on Snapchat, and engaging in sexual activity with the boy at Davis’s Manhattan apartment in June, according to the complaint.

“Having started an organization that pushed for the end of sexual violence, Davis displayed the highest degree of hypocrisy by his alleged attempts to sexually exploit multiple minors,” FBI Assistant Director-in-Charge William F. Sweeney Jr. said. “As if this wasn’t repulsive enough, Davis allegedly possessed and distributed utterly explicit images of innocent infants and toddlers being sexually abused by adults.”

Authorities came across Davis when an FBI agent posted a message on a “fetish” website where people leave ads soliciting children for sex, according to the criminal complaint.

“Looking for other no limits TABOO pervs in DC area,” read the message posted by the FBI. “Bi dad here.”

A person with the screen name “yngperv22″ responded saying: “Need me to come down and watch ur kids for a night : ).” That person was subsequently identified as Joel Davis, according to the criminal complaint. Davis exchanged phone numbers and began texting the original poster, not knowing he was an undercover FBI agent.

Davis told the agent that he is into children ages zero and up, and has “[n]o limits,” according to the complaint. He said he previously had sexual experiences with a 9-month-old boy, a 6-year-old girl and a 7-year-old boy. He sent the agent an array of disturbing photos showing toddlers performing oral sex on adults and images of adults sexually abusing naked children as young as infants.

He asked another undercover agent to take nude pictures and videos of the agent’s supposed 9-year-old daughter and the 2-year-old daughter of the agent’s girlfriend. Davis told the agent he had “hundreds” of images of child pornography in his “collection,” mostly “baby/toddler.”

Davis pressed the agent about meeting the 2-year-old girl. “When do u have that baby alone next,” Davis asked. “I mean even for a few mins enough to FaceTime.”

Through a search warrant, authorities later recovered a trove of child pornography on Davis’s cellphone. After his arrest, Davis admitted to having a sexual interest in infants and toddlers, keeping the child porn on his phone, and trying to set up meetings with the agents’ children, authorities said.

U.S. Attorney Geoffrey S. Berman, in the Southern District of New York, said in a statement that Davis’s alleged conduct “is as unfathomable as it is sickening.”

“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,” Berman said.

Indeed, Davis allegedly appeared to live a double life. He described himself a “human rights defender” and was frequently called upon as a reputable speaker on issues of sexual violence. In 2016, he appeared on an Al Jazeera English segment titled, “Rape as a weapon of war: The untold story of armed conflict.”

“Sexual violence intensifies and diversifies in conflict,” he said while speaking about countries like Syria and the Congo. “The challenge again is to see how we end sexual violence in areas of post conflict, and we know it’s not just armed groups perpetrating sexual violence.”

In a 2014 article in the HuffPost, Davis specifically wrote about young people victimized by sexual violence. “In so many conflicts across the globe, children’s bodies are quickly becoming sites of violence, where rape is used to terrorize and degrade entire communities,” he wrote.

After graduating from high school in Port Charlotte, Florida, Davis spent a gap year working at the United Nations, he claimed in a student newspaper article. He claimed to have attended American University in Washington before transferring to Columbia University, where he studied in the School of General Studies, according to the Columbia Spectator.

According to his LinkedIn profile, he also studied classical piano at the prestigious Juilliard School through an exchange program with Columbia.

The Post could not independently verify this and other claims.

In 2015, he was one of more than 200 individuals and organizations nominated for the Nobel Peace Prize, according to a Florida NBC affiliate that reported the news at the time. The source of that information, other than Davis, wasn’t clear from the article.

While anyone can be eligible for the prestigious award, only certain people can submit nominations, according to the Nobel Peace Prize’s website. These include members of national governments and international courts, university professors, former Nobel Peace Prize winners and members of the Norwegian Nobel Committee.

As a columnist for the Columbia student newspaper, Davis opened up about overcoming his own experiences with sexual assault.

“When news broke that I was being considered for a Nobel Prize, I had a psychological breakdown – tormented by the recollection of my childhood sex abuse – and withdrew from Columbia,” Davis wrote in the Columbia Spectator. “It was another year before I attended my first class.”

In another piece, Davis said he was working on an upcoming novel about the effects of trauma on a relationship. He planned to title it, “Benevolence.”

He even wrote about grappling with his PTSD through therapy sessions with a psychologist.

“She dubbed my behavior ‘extremely self-destructive’ and explained that I was putting myself in precarious situations to assert some sense of control,” Davis wrote of his psychologist. “Sometimes, when you feel like your life is falling apart, quickening the inevitable descent into pariahdom seems like the only thing left to do.”

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