A man in custody at Denver’s Downtown Detention Center died Friday morning, marking the second inmate death to occur at the jail this month.

Denver County Sheriff’s Department deputies found a man unresponsive in a housing unit at the Downtown Detention Center — located near Civic Center Park — around 12:30 a.m. Friday morning, according to a news release from the department.

A medical emergency team was immediately called and performed “life-saving efforts,” the department said. The man was then taken to Denver Health Hospital, where he was pronounced deceased.

The Denver Police Department has opened a death investigation, per protocol. The identity of the man will later be released by the Denver Office of the Medical Examiner following an autopsy and family notification.

This is the second inmate death at the jail this month.

Another inmate — later identified as 53-year-old Phillip Martinez — was found unconscious in a housing unit on May 16. He later died at a nearby hospital, as well.

The Denver Office of the Medical Examiner did not release the cause and manner of death pending further investigations by the police department.