He angered many in Cambodia when he drew up a government “white paper” that justified a coup in 1997 by Mr. Hun Sen, arguing that his seizure of full leadership from his co-prime minister, Norodom Ranariddh, had in fact been carried out to prevent a coup.
Mr. Sciaroni was born in Los Angeles in September 1951, the son of a doctor, and grew up in Fresno, Calif.
He received a master’s degree in international affairs from Georgetown University in Washington and a law degree from the University of California, Los Angeles. He then worked for conservative policy associations before joining the Reagan administration, where he worked on arms control and commerce before moving to the Intelligence Oversight Board.
In Cambodia, according to a friend, he lived by an unchanging routine: arriving at and leaving his office early, then visiting a fixed circuit of bars, where he regularly tipped the waitresses two dollars each, a considerable sum for working Cambodians.
He called himself a devout Roman Catholic but said his regular bedside reading was not the Bible but “A Confederacy of Dunces,” a picaresque novel by John Kennedy Toole, which he opened at random before falling asleep.
He is survived by his wife, Bui Thi Hoa My; their daughter, Patricia; and two brothers.
“Brett was terrific, personally and professionally,” recalled Luke Hunt, a Phnom Penh-based foreign correspondent and columnist for The Diplomat, an online current affairs magazine. “He ranked among the handful of foreigners who genuinely knew Cambodia and the powers that made it work.”