When his brother Sanjay Gandhi died in a plane crash in 1981, Rajiv Gandhi—then an airline pilot—was drafted into politics by his mother, Indian Prime Minister Indira Gandhi. When she was assassinated in 1984, he succeeded her as prime minister. In 1987, he sent peacekeeping forces to Sri Lanka in an unsuccessful attempt to end Tamil-Sinhalese violence. Following allegations of corruption, he resigned as prime minister in 1989. He was assassinated in 1991. How and by whom was he killed?