How a Sensational, Unverified Dossier Became a Crisis for Donald Trump – The New York Times

The story began in September 2015, when a wealthy Republican donor who strongly opposed Mr. Trump put up the money to hire a Washington research firm run by former journalists, Fusion GPS, to compile a dossier about the real estate magnate’s past scandals and weaknesses, according to a person familiar with the effort. The person described the opposition research work on condition of anonymity, citing the volatile nature of the story and the likelihood of future legal disputes. The identity of the donor is unclear.