|Sergei Kirov, a close associate of Stalin, was assassinated . This prompted Stalin to institute another great purge. In the previous year, Stalin had purged the Communist Party of close to 1,000,000 members. This time, many of the older leaders of the party, such as Zinoviev and Kamenev, were arrested and tried for treason. Before the purges ended, close to 8 million people were killed, imprisoned or sent to Siberia.