Alison L. Des Forges, a human rights activist and historian who tried to call the world’s attention to the looming genocide in Rwanda in 1994 and who later wrote what is considered the definitive account of the eventual slaughter of more than 500,000 Rwandans, was among the passengers killed Thursday when Continental Airlines Flight 3407 crashed near Buffalo. She was 66 and lived in Buffalo.

Her death was confirmed by Human Rights Watch, the New York-based advocacy group; Dr. Des Forges was senior adviser for its Africa division for nearly 20 years.

Although she lived in Buffalo, Dr. Des Forges (pronounced deh-FORZH) spent much of her adult life in Rwanda and the Great Lakes region of Africa. She was among a group of activists who investigated killings, kidnappings and other rights abuses of civilians in Rwanda from 1990 to 1993.

In May 1994, several weeks into the mass killing of Rwanda’s Tutsi minority, Dr. Des Forges called for the killings to be officially declared a genocide. By then about 200,000 people had been killed.