A Chester County man who was to stand trial in the severe beating of his girlfriend’s daughter died last week in the county jail, officials said Thursday.

Dimitrios Moscharis, 34, of West Chester, was found dead inside his cell last Friday, according to a county spokesperson. The cause of his death remained under investigation and no other information was available Thursday.

Prosecutors said Moscharis attacked his girlfriend’s 9-year-old daughter under the guise of discipline. District Attorney Deborah Ryan characterized his actions as tantamount to torture. She said he would lock the child in a closet for hours, beat her with a curtain rod, and force her sleep on a concrete basement floor.

» READ MORE: Chester County couple heading to trial in severe beating of girl

Moscharis was arrested in November by Westtown Township police after they were called to the home he shared with Julianne Lewis, the girl’s mother, for reports of a child in cardiac arrest. The girl, covered in bruises and unresponsive, was taken to Nemours A.I. DuPont Hospital for Children.

She had serious injuries to her lungs and eye from what detectives called “a near fatality.”

Moscharis was charged with attempted murder, strangulation, aggravated assault, child endangerment, and related charges. During his preliminary hearing in December, prosecutors added an additional charge of involuntary deviate sexual intercourse with a minor after finding evidence of sexual assault.

The child’s mother told investigators she had been dating Moscharis for about six weeks, and that she had given him permission to “discipline” her daughter. Lewis often left the girl in Moscharis’ care while she worked multiple jobs, authorities said.

» READ MORE: West Chester man severely beat a 9-year-old, leaving her with near fatal injuries, DA says

Investigators uncovered internet searches on Lewis’ computer showing that in the days before her daughter was rushed to the hospital, she had researched how to put a child up for adoption. She was charged with false imprisonment of a minor, simple assault, endangering the welfare of a child, and related offenses. Her criminal case is pending.