This is physically painful to write for me, but a lot of theories about the measureable threshold for death, the raw data on how long it takes tissue to no longer be recoverable after exposure to certain pathogens, exsanguination, timetables for tissue to freeze, time for frozen tissue to die, physiological limits of anoxia etc were "fleshed out" as it were by unit 731 and Mengele & friends. Most of the scientists and physicians of Unit 731 were given the option of either working for the DoD at Ft Detrick (history, farce etc) or facing Chinese justice.

tldr The American government officially said everything was destroyed but as is longstanding tradition with war criminals we gave everyone jobs,