Cambridge Analytica was heavily funded by the family of Robert Mercer, a hedge fund manager who also backed the campaign and other conservative candidates and causes. Cambridge Analytica also worked for the successful pro-Brexit campaign in 2016 to pull Britain out of the European Union. Steve Bannon, Trump’s chief strategist, was a vice-president of Cambridge Analytica before he joined the Trump campaign. The firm was effectively a shell. According to the documents and former employees, any contracts won by Cambridge, originally incorporated in Delaware, would be serviced by London-based SCL and overseen by Alexander Nix, a British citizen who held dual appointments at Cambridge Analytica and SCL. Most SCL employees and contractors were Canadian or European. But in July 2014, an American election lawyer advising the company, Laurence Levy, warned that the arrangement could violate laws limiting the involvement of foreign nationals in American elections. As Cambridge Analytica seeks to expand its business in the United States and overseas, Mr. Nix has mentioned some questionable practices. He boasted of employing front companies and former spies on behalf of political clients around the world, and even suggested ways to entrap politicians in compromising situations.