alt Hacker News> From that list of 40 or 50 people, it was easy to find and trawl their social media. And that is when they found a photo of Lucy on Facebook with an adult who looked as though she was close to the girl - possibly a relative.
It sounds like Facebook was a huge boost to the investigation despite that.
Facebook did nothing to assist in narrowing a search area.
What Facebook actually did was host images .. so that after the team narrowed a list down to under 100 people they could look through profiles by hand.
It may as well have been searching Flickr, Instagram, Etsy, etc. profiles by hand.