Gave the order for the assassination of Leon Trotsky, an exile in Mexico in in 1940.

Named Deputy Prime Minister in February 1941, in charge of Russian security after the invasion by the Germans. He used this opportunity to murder as many old Bolsheviks as he could, thus eliminating as many of Stalin's old political rivals as he could. He began a horrific purge, going so far as to order the mass execution of more than 10,000 political prisoners he had sent to detention camps.

Was named a member of the State Defense Committee and was named Marshall of the Soviet Union in 1945. Was made a full member of the Soviet Politburo in 1946. Was eventually put in charge of Atomic bomb development.

Was viewed by many as a distasteful monster, believed to be a sexual predator, accused of raping and sodomizing young girls and threatening their families to keep them quiet. Gave the NKVD a makeover, renaming it the MVD, In addition to massive internal investigations and purges, Beria oversaw the implementation of a worldwide espionage system, aimed at gathering intelligence from the west.

As had happened with his predecessors, Beria fell out of favor with Stalin due to Stalin's continued paranoia. Stalin, feeling Beria possessed too much power, feared that his top policeman would attempt to overthrow him. Believing that Beria had set in motion a plot to assasinate him, Stalin ordered him arrestes. Stalin died soon thereafter (some belive Stalin suffered a stroke while speaking alone with Beria).