A man in custody at the DeKalb County Jail died on Memorial Day in an apparent suicide, authorities said.

Enil Guillen, 20, of Doraville, was found hanging unresponsive in his cell Monday, according to DeKalb sheriff’s office spokeswoman Cynthia Williams. Guillen was given first aid by the jail’s on-site health staff and DeKalb emergency medical personnel, but he could not be revived, Williams said.

The incident remains under investigation by the sheriff’s Office of Professional Standards, Williams said.

“Preliminary reports indicate suicide as the possible cause of death,” she added.

Guillen was booked into jail May 11 on a felony count of theft by taking and a misdemeanor count of driving without a license, the sheriff’s office said.

Online records show that Guillen had been booked into the county jail six times since November by Dunwoody, Chamblee and DeKalb police, though his past charges were all misdemeanors. He was previously charged in another state with felony theft by taking, but those charges were dropped, according to jail records.