A suspect in the suicide death of an Air Force sexual abuse victim has been found dead at a military detention facility, a human rights group said Monday.

The senior master sergeant was indicted on charges of inflicting secondary harm and threatening retaliation against the master sergeant who took her own life in May, three months after she was allegedly groped and suffered other abuse by a colleague of the same rank.

"The senior master sergeant was found unconscious at 2:55 p.m. Sunday and transferred to a civilian hospital but later died," the Center for Military Human Rights Korea, a nongovernmental organization, said.

The suspect had been held at a detention facility run by the military police.

The rights group blamed the Ministry of National Defense for poor supervision, saying the senior master sergeant required careful monitoring as a suspect in a high-profile case and that the incident occurred "in broad daylight."

The group also claimed the suspect's death will hamper efforts to get to the bottom of the case as it occurred before the related trial is set to begin on Aug. 6.

"Investigation authorities are looking into the exact cause of his death," defense ministry spokesman Boo Seung-chan said during a regular press briefing. (Yonhap)