https://www.theregister.co.uk/2017/10/13/facebook_and_twitter_slammed_for_deleting_evidence_of_russian_election_interference/

Facebook and Twitter have come under attack for deleting tens of thousands of posts that may provide vital clues to how and to what extent the Russian government was able to able to influence the US presidential elections.

Facebook has removed thousands of Facebook posts – and the related data around them such as "likes" and shares – and also deleted them from its cache of inactive Facebook pages.