NEW YORK (AP) — The head of New York City's jails system says an investigation has been launched into the death of a mentally ill veteran who city officials tell The Associated Press died in an overheated cell.

Acting Department of Correction Commissioner Mark Cranston says in a statement that the temperature in 56-year-old Jerome Murdough's cell was "unusually high."

Four city officials tell the AP Murdoughwas found dead last month in a cell that was at least 100 degrees in a unit for inmates with mental illnesses at Rikers Island.

They say Murdoughapparently didn't open a small vent to let cool air in and was on anti-psychotic medication that made him more sensitive to heat.

The officials spoke on the condition of anonymity because they were not authorized to discuss the investigation.

(Story by: Jake Pearson, The Associated Press with minor editing by WIBX)