STOCKHOLM (Reuters) - Swedish prosecutors investigating a suspected gang rape and its broadcast via Facebook Live said on Friday they had received a copy of the footage from the U.S. social media company.

Prosecutors earlier this month charged two men with raping a woman in January, and a third with the crime of “grave defamation” by streaming it live or with a slight delay online. The three deny the charges.

“We have received the material,” Prosecutor Magnus Berggren told Reuters, saying he had confirmation that the alleged assault had been streamed live.

Sweden made a formal request to the U.S. justice department for help in obtaining the footage from Facebook. Police were alerted to the case by viewers who saw the broadcast.

The case brings into focus complex ethical and policy issues faced by Facebook Live and other streaming services.

Facebook Live allows anyone to broadcast a video directly from their smartphone without the regulatory restrictions imposed on traditional broadcasters.

Facebook was not immediately available for comment on Friday.

It said on March 15 it responded to valid requests relating to criminal cases. “We support local law enforcement who make data requests related to criminal investigations, particularly when it comes to the safety of young people,” it said in a statement to Reuters.