From hackread.com
Facebook paid a cybersecurity company to develop a hacking tool exploiting zero-day in Tails OS used by the abuser ultimately leading to his hack, track, and arrest.
Taking an unprecedented step to help the US Federal Bureau of Investigation (FBI) identify and capture a criminal, Facebook played a key role in tracking down Buster Hernandez, a/k/a Brian Kil, a/k/a Purge of Maine, a habitual child predator.