© NBCWashington.com
Mannina, 58, was arrested last week in connection with a violent home invasion at the residence of one of his coworkers.
He was "found unresponsive on the bunk in his cell by facility security staff" around 3:45 a.m. Tuesday, D.C. police said. Police said in an official release that the cause of death is under investigation.
Mannina had been in custody since Thursday following a June 5 incident at his coworker's home on Chesapeake Street NW.
According to charging documents, the victim told detectives she was expecting Mannina to visit her that morning and she let him into her home.
She said he briefly walked back out to his car to get his camera to "take photographs of her cat," but he returned with a red gym bag and used a stungun on her while her back was turned.
He then allegedly struck her in the face several times, used pepper spray on her and handcuffed her hands behind her back. Police said he also attempted to sexually assault her.
The woman said he eventually let her go, and she led him out of the home and drove herself to a hospital. She had been beaten so badly that a plate had to be surgically implanted in her face, The Washington Post reported.
Mannina was arrested June 13 at a Montgomery County-area hospital following what was reported to be a suicide attempt.
He was charged with third-degree sexual abuse and first-degree burglary. If convicted, Mannina could have served up to 30 years on the burglary charge and up to 10 years on the sex abuse charge.
30 years burglary
10 years on sex abuse
Good to know where we stand ladies?