While twelve Unit 731 researchers arrested by Soviet forces were tried at the December 1949 Khabarovsk war crimes trials, they were sentenced only to the Siberian labor camp from two to 25 years, seemingly in exchange for the information they held.

All of the defendants (aside from one who died in prison and another who committed suicide) had been freed by 1956, a mere seven years after the trial took place.

This your source?

[–] Shareni@programming.dev 0 points 2 months ago

Ok that's my bad, the allies were hanging Japanese, not the Soviets themselves.

The point still stands though about USA saving them from hanging...

Due to U.S. government intervention, the trials did not charge imperial Japanese leaders who may have been responsible for Unit 731.

https://en.m.wikipedia.org/wiki/International_Military_Tribunal_for_the_Far_East#Defendants