what type of torture methods did the interrogators at the gulags use to get prisoners to admit to crimes they never committed

Some of the torture methods that interrogators used to get prisoners to admit to crimes were having prisoners skulls squeezed within iron rings, exposing their naked bodies to be bitten by ants and other different bugs and being stopped from sleeping for a week.

Explanation:

The gulag was a Russian government agency created by Vladimir Lenin, the agency was in charge of the soviet forced labor camp system. The camp contained an extremely large number of convicts.