Facebook relies heavily on machine learning to detect and delete fake accounts, spam, malware and much more. However, there are plenty of cases illustrating that AI alone may not be enough to police the largest social network in the world. A report from NBC News this week illustrated the heartbreaking human cost of allowing these fake profiles to remain active on the platform.

In one example, a 22-year-old police officer was killed in the line of duty just six months into the job in Tecumseh, Oklahoma. Then a year later, a fake profile using the officer’s name and pictures appeared out of nowhere. And when authorities tried to get Facebook’s attention regarding the account, they couldn’t make headway.

“I couldn’t believe that someone would stoop that low,” Chief of Police J.R. Kidney told NBC News. “Our response from Facebook has been zero. I haven’t heard anything from Facebook, they’ve never contacted us at all.”

In another case, a young mother discovered that photos of her one-year-old twins had been stolen and used for a page that claimed the twins’ parents had died.

Incidents like this are disturbing, but experts say we shouldn’t expect Facebook to change anytime soon. The platform is so enormous, and so simple to use, that it’s almost impossible to catch every scammer.