Controlling the spread of content on social media platforms is difficult, if not impossible. Once something is posted on Facebook, there’s little that can stop it from being copied or reposted again and again. That’s the problem Facebook faces this week after police issued warrants to the site aiming to discover if more copies exist of a Facebook Live video depicting a sexual assault.

The disturbing video was first live-streamed on July 11. What’s worse, it went viral, and was viewed 48,000 times before being removed. Now police want to know if more copies of the video are out there.

“Investigators want to know if Facebook has any more video available,” attorney Herman Cox said. “What they’re thinking is Facebook may have other video than what was shared before Facebook stored the original video, and what else people may have shared.”

It’s noble that police want to track down every copy of this horrific video, but it’s a sad truth of the Internet that they probably can’t. Once something gets publicly posted on Facebook, it can’t be made private again. That’s why it’s so vitally important to be careful what content you post on social media in the first place.