F1,

It's in best interest of community and law enforcement to root out rogue cops.
I think the manufacturer of the recording devices in their squad cars had to help investigators retrieve data that she tried to hide/conceal.

http://www.ajc.com/news/news/breaking-news/cop-made-up-story-about-georgia-shooting-gbi-says/nsdct/

Hall’s account continued to come apart as investigators and law enforcement officials spent more than 600 hours examining the case, Wooten said.

At first, she said she failed to “engage her in-car video and audio,” so there was no evidence to back her up. But Wooten said the manufacturer helped recover digital forensic evidence that showed “inconsistencies.”

After Hall was again interviewed, she stopped cooperating with the GBI.

With cameras, it's not up to cops to tell on other cops, which is another reason I think police unions are fighting mandatory recording.