Alex Stamos, Facebook’s chief security officer who helped track down how Russia harnessed the network for its 2016 disinformation campaign, is under a spotlight and reportedly set to resign later this year amid fallout over the social network's work with a data mining firm used by the Trump campaign. The social network is reeling from revelations that data for 50 million users was harvested by Cambridge Analytica, and facing renewed scrutiny from lawmakers on both sides of the Atlantic, putting Stamos’s future at Facebook in doubt.