A628. "Show Me the Man and I'll Find You the Crime"
That's what Stalin's henchman, Lavrentiy Beria, is quoted as saying. He played a key role in Stalin's rule, and was seemingly always loyal to him. He was probably most widely recognized for his long-time position as head of the secret police--mandated to bring to "justice" any people that Stalin wanted to get rid of. He was also the only one permitted to wear a pistol to Politburo meetings--in Stalin's presence.
Apparently, however, he also deserves credit for doing something infinitely more important. After the US deployed the A-bomb against Japan, Stalin assigned Beria --in addition to, not instead of, everything else he did--to develop nuclear weapons for the USSR. Beria was not a scientist!
To this end, the Soviets were receiving inputs from some notorious American "atom spies"--and possibly from some in others in Allied countries. But history recounts that Beria initiated a remarkable rule for the Soviet nuclear program. Information from foreign sources was to be applied only to confirm what his own scientists had already learned. The foreign intelligence was not to be used to guide or direct his own team's research.
Maybe this was an excellent policy, given the possibilities that there were double agents, or just confusion in the data they delivered. One way or the other, his program was a brilliant success, and Stalin got nuclear weapons in only a few more years. Beria succeeded--where Hitler had failed! But not too long afterwards, in 1953, he was executed for treason after a coup by Khrushchev. He had been one in a triumverate of Stalin's successors. I'd say the other big shots were scared to death of him!
During Stalin's lifetime, Beria was putatively responsible for quite a few genocidal actions. These did not entail any accusation or prosecution at the individual level. It was enough that the people killed belong to an offending group, for instance, the Katyn Massacre of Polish officers (22,000 people).
However, the quote at the top relates to his NKVD activity. If Stalin wanted someone killed, Beria prided himself on being always able to come up with some terrible crime the person had committed. This is an extreme feat in the use of "prosecutorial discretion."
The basic idea is first to choose the inconvenient or disloyal person, and then find some crime to hang on him. In today's Russia, and to a lesser extent China, it can be "tax evasion," at least when a company is involved. Or, like the pitiful 1000 "insurrectionists." Or, like Trump himself--where the search for a crime has already taken two years.
Why so long? I'd say it's because Biden hadn't decided whether it was better or worse to run against Trump--and what effect (possibly favorable!) an indictment would have on Trump's candidacy.