Anonymous claims to have a confession from a suspect who allegedly raped Rehtaeh Parsons, who was recently taken off life support after a suicide attempt.
The hacktivist group threatened to reveal the identity of the teenaged suspect and three others accused of the 2011 gang rape of the Canadian teen.
Anonymous was drawn to the case following outcry about Rehtaeh Parsons' death, and called on the Royal Canadian Mounted Police to make arrests.
The group said in a statement: "A 17-year-old girl killed herself because the police failed to do their jobs and charge a single person for any of them."
"Why is Anonymous involved in this case? We are involved because the facts clearly illustrate that several crimes have been committed in Nova Scotia."
Her parents said she hanged herself last week, not only because she was sexually assaulted but because photos of the attack were shared by the alleged rapists.
Classmates at her school tormented her afterward, drawing tragically similar parallels with the death of raped and bullied California teen Audrie Pott.
According to Anonymous, one of Parsons' alleged attackers:
"Made several public statements admitting that he did have sex with [Rehtaeh] on the night in question" and that "she was throwing up during the act."
The confession the group claims to be in possession of includes the names of three other boys who allegedly "took turns having sex with [Rehtaeh]."
Anonymous said it has already shared the information it pieced together, including screenshots of the alleged confession, with local law enforcement.
With public pressure mounting, Nova Scotia's Justice Minister Ross Landry announced on that his department would reopen the case, the CBC reported.
Anonymous is a loosely connected collective of skillful hackers and Internet activists, but one that has left its mark on many a case in recent years.
They famously drew attention to a video of Steubenville (Oh.) H.S. students joking about rape, and trolled the crap out of the Westboro Baptist Church.