"Sergeant A" doesn't want to give his real name, his exact rank or show his face.

Speaking to CNN, he said he was afraid the South Korean military would find out he was talking to the media. He faces charges for having sexual relations with another man, a crime within the South Korean military punishable by up to two years in prison. Sergeant A is part of a wider investigation which human rights groups are calling a homophobic witch-hunt, an accusation the military rejects.

Homosexuality is not illegal for civilians in South Korea but human rights groups say the rights of sexual minorities are not always protected.

Investigators visited Sergeant A in March -- telling him they knew he was gay and his ex-partner had already admitted their "crimes." They asked him deeply personal and explicit questions, leaving him feeling "uncomfortable and humiliated," Sergeant A told CNN.

"The atmosphere was very oppressive and humiliating," he said. "I was scared."

The South Korea military and the defense ministry declined multiple requests for an interview and referred CNN to an April statement. Read more and watch the video from CNN