This app was mentioned in 2 comments, with an average of 5.50 upvotes
I don't think he was a hacker.. He is a journalist using some software available on the play store (and apple app store) called "find face"
You can use this app to search them by their face:
https://play.google.com/store/apps/details?id=ru.trinitydigital.findface&hl=en
Pretty solid app from what I heard on Pikabu.
You can also use their website (need a VK account):