Complex sentence: Nolting asserted that Mecklin was psychologically vulnerable after his wife had left him, and that he had been brainwashed by his roommates-at the time, Mecklin was living with journalists David Halberstam and Neil Sheehan of the "New York Times" and UPI respectively.
Split into simpler sentences: Nolting asserted that Mecklin was psychologically vulnerable after his wife had left him and had been brainwashed by his roommates. At the time, Mecklin was living with journalists David Halberstam and Neil Sheehan of the "New York Times" and UPI respectively.