Answer
Vavilov died in prison after being falsely accused of spying for the West. He had been imprisoned in 1940, after Stalin began his purge of the Soviet Union's scientific community. Vavilov was accused of being a "Trotskyite" and a "foreign spy," and he was sentenced to death in 1942. However, his sentence was commuted to 20 years in prison, where he died in 1943.