The Tor Project confirmed today that one of its prominent developers, Jacob Appelbaum, stepped down in response to what it called “public allegations of sexual mistreatment.” The Tor Project, which develops the Tor browser and network, had previously only acknowledged Appelbaum’s departure in a one-sentence statement Thursday afternoon, but went into further detail about his resignation after rumors of assault emerged online.

Tor is free software that channels internet traffic through a series of relays to anonymize its users. In addition to his security research at the Tor Project, Appelbaum is a journalist who worked on WikiLeaks and the Edward Snowden disclosures. Rolling Stone called him the “public face of the Tor Project” in a 2010 profile that detailed his involvement with Tor and WikiLeaks. Before joining Tor, Appelbaum worked on security for Greenpeace and the Rainforest Action Network.

Tor Project executive director Shari Steele said in today’s statement that allegations of sexual assault had followed Appelbaum for quite some time. “These types of allegations were not entirely new to everybody at Tor; they were consistent with rumors some of us had been hearing for some time. That said, the most recent allegations are much more serious and concrete than anything we had heard previously,” Steele wrote.

Steele added that The Tor Project had heard allegations from several victims about Appelbaum’s behavior towards them. The Tor Project has hired a legal firm to investigate the statements, but Steele said she did not expect that the results of the investigation would be made public.

Steele initially announced Appelbaum’s resignation in a simple statement on Thursday: “Long time digital advocate, security researcher, and developer Jacob Appelbaum stepped down from his position at The Tor Project on May 25, 2016,” she wrote.

Despite the terse announcement, the backstory of Appelbaum’s resignation quickly emerged online.

Andrea Shepard, a Tor developer, tweeted the decoded version of a message she’d originally posted on May 24, one day before Appelbaum stepped down. “It seems one rapist is one rapist too many,” she wrote. (SHA-256 references the hash used to encode the original message.)

Precommitment revealed: sha256("It seems one rapist is one rapist too manyn") (https://t.co/gUpiPKI0st) — Andreⓐ (@puellavulnerata) June 3, 2016

Alison Macrina, the founder of The Library Freedom Project, also referenced the allegations on Twitter, saying she had spoken to several victims. The Library Freedom Project is an organization that educates librarians about privacy and collaborates with the Tor Project to establish Tor exit nodes in libraries. “no more open secrets, no more missing stairs. you’re not alone. you were never alone. and I’m pretty sure things are just getting started,” Macrina tweeted.

Several anonymous accounts of assaults allegedly committed by Appelbaum were also posted on a website bearing his name, but TechCrunch has not yet been able to verify them.

Steele said the Tor Project would work to foster a safer environment. “Going forward, we want the Tor community to be a place where all participants can feel safe and supported in their work. We are committed to doing better in the future. To that end, we will be working earnestly going forward to develop policies designed to set up best practices and to strengthen the health of the Tor community,” Steele wrote.

Update 6/6: Appelbaum posted a response to the allegations against him on Twitter, saying they are part of a “calculated and targeted attack” intended to undermine his advocacy work.

“I want to be clear: the accusations of criminal sexual misconduct against me are entirely false,” Appelbaum wrote. “Though the damage to my reputation caused by these allegations alone is impossible to undo, I nonetheless take the concerns of the Tor community seriously.”

Appelbaum suggested that he would sue his accusers if necessary to clear his name, calling the allegations libelous. His full statement is here.