An investigation has begun into the death of 56-year-old Jerome Murdough, a mentally ill homeless military vet who died in his Rikers Island jail cell on Feb. 15. Murdough had been arrested and charged with trespassing after being discovered sleeping in an enclosed stairwell on the roof of a public housing project in East Harlem.

“Mr. Murdough violated the trespass law, so he suffered the consequences by going to jail,” attorney Jennifer Parish of the Urban Justice Center’s Mental Health Project told the Associated Press. “But the jail system committed more serious harm to him, and the question is, will they ever be held responsible?”

According to city officials, Murdough was incarcerated alone in a 6-foot-by-10-foot cinderblock cell at Rikers Islands’ mental observation unit at about 10:30 p.m. on Feb. 14, a week after his arrest. There, he was supposed to be monitored every 15 minutes as part of a suicide watch, but he was left unattended for approximately four hours. At about 2:30 a.m. the following day, he was discovered slumped over in his bed, already dead.

“He basically baked to death,” said one of the city officials, who all spoke on condition of anonymity.

Officials estimated the temperature in his cell reached over 100 degrees, apparently due to malfunctioning equipment. Reports say that vents were not opened that ordinarily would have provided adequate air circulation and allowed lower temperatures. They also stated that the lack of supervision constitutes a violation of standard procedure. They suggested that correction officers are not sufficiently trained to deal with mentally ill inmates whose needs are complex.

“He was a very lovely, caring guy,” said his 75-year-old mother, Alma, who added that her son suffered from bipolar disorder and schizophrenia. “He had beer problems. Drinking beer, that was his downfall … other than that, he was a very nice guy. He’d give you the shirt off his back.”

Murdough reportedly took anti-psychotic and anti-seizure medicine, which officials say may potentially have made him more susceptible to heat, while early autopsy reports suggest he died of extreme dehydration or heat stroke. “Psychotropic medications can impair the body’s ability to cool itself by sweating, making it retain more heat than it should,” reads the report.

The medical examiner’s office stated that autopsy results were inconclusive and that further tests were necessary in order to pinpoint the cause of death, while the Department of Correction has initiated an internal investigation.

“We want justice for what was done,” demanded Murdough’s sister, Wanda Mehala. “He wasn’t just some old homeless person on the street. He was loved, he had a life, he had a family, he had feelings.”

Department of Correction spokesman Robin Campbell said in a statement that an internal investigation looking into all circumstances of Murdough’s death is ongoing, “including issues of staff performance and the adequacy of procedures.”