Trump Team Knew Flynn Was Under Investigation Before He Came to White House - The New York Times

WASHINGTON — Michael T. Flynn told President Trump’s transition team weeks before the inauguration that he was under federal investigation for secretly working as a paid lobbyist for Turkey during the campaign, according to two people familiar with the case.
https://www.nytimes.com/2017/05/17/us/politics/michael-flynn-donald-trump-national-security-adviser.html