A North Korean nuclear scientist who defected to China committed suicide after being forced to return, Radio Free Asia (RFA) reported Thursday. The defector was a researcher at the physics center in the State Academy of Sciences in Pyongyang, the report said.

The scientist was identified as Hyun Cheoi Huh, though RFA clarified it was unclear whether that was his real name. The man reportedly took a leave of absence from his job at the academy before defecting.

He was sent back to North Korea on Nov. 17, RFA reported.

“He killed himself only a few hours after he was placed in solitary confinement at the State Security Department in Sinuiju city,” a source told RFA, speaking on the condition of anonymity. “He died before he could be questioned about the reasons for his escape, and what his route had been.”

The man took poison inside the security cell where he was set to be questioned. It remained unclear how he smuggled the poison inside. 

The man was detained in China and sent back to North Korea. It appeared he had kept his occupation a secret when he was detained, RFA reported, though it was unclear why.

“If the Chinese government had known who he was, they would have wanted to learn what he knew and would never have sent him back,” the source said.

The extreme situation among defectors after fleeing North Korea is not unheard of. A 24-year-old soldier who ran across the border to South Korea in November told a doctor he was suffering nightmares about being sent back. The unidentified man said he was plagued by worries he would be forced back after being shot by his own fellow soldiers as he fled.

Another defector, who escaped to South Korea in 2015, said he carried poison with him to take in case he was captured.