The left certainly has a long memory.
Who’s next on their list? Sacco and Vanzetti?
A very god suggestion or guess.
The "litterati" who later research has shown in so many cases were fellow travelers or even witting agents for the Soviets were enticed and run by Will Müntzenberg - a Leninist and later Stalinist agent. One of his first successes was the Sacco and Vanzetti case.
If you have not read "Double Lives: Stalin, Willi Münzenberg and the Seduction of the Intellectuals" by Stephen Koch I highly recommend it.