https://www.reuters.com/article/us-facebook-propaganda-mueller/facebook-gives-election-ad-data-to-u-s-special-counsel-source-idUSKCN1BI03V

Facebook Inc has turned over information about U.S. election ads it believes were bought by Russians to Robert Mueller, the special counsel in charge of investigating alleged Russian interference in last year's election, a source familiar with the matter said on Wednesday.