A Sonoma County jail inmate died early Wednesday. The 31-year-old man had just begun a 15-day sentence for a drunken- driving conviction, sheriff’s officials said Wednesday afternoon.

Diego Armando DePaz of Santa Rosa was found in his dorm bunk, unresponsive, as inmates were awakened for the day, sheriff’s Sgt. Cecile Focha said in a news release. Medical attempts to revive him failed, and he was declared dead at 5:14 a.m.

Investigators with the Sonoma County Sheriff’s Office and District Attorney’s Office are investigating.

Because his cause of death wasn’t immediately apparent, sheriff’s officials have asked the Marin County Coroner’s Office to conduct the autopsy and related pathology testing, sheriff’s Lt. Carlos Basurto said.

“There were no obvious signs of trauma to his body,” Basurto said. “It’s unclear whether it was a medical issue or some other reason.”

DePaz is the second man in just over a week to die while incarcerated in Sonoma County.

Mikol Stewart, 36, of Santa Rosa died Sept. 28 after reportedly hanging himself in his cell. The homicide suspect was being held in the county’s main jail at the county administration center in Santa Rosa.

Basurto said there was no reason to think the deaths were connected or part of any sort of trend. “One was a suicide and the other, well, we just don’t know at this point,” he said.

The investigation of Stewart’s death is finished, Focha said, and a report was being compiled to turn over to the Sonoma County District Attorney’s Office.

DePaz was sentenced Sept. 30 after being convicted of an October 2013 drunken-driving case in Santa Rosa. He turned himself in to the North County Detention Facility on Monday at 7:07 p.m. to start his 15 days in jail.

Focha said he was evaluated for medical and psychological issues and no concerns were noted.

In his short time at the jail, the man hadn’t shown any signs of a medical problem or behavior issues. He’d also not been assigned to spend the day on a work crew outside of the jail, she said.

On Tuesday night, a jail officer locked down the dorm at 11 p.m. During the night, two checks were made of the dorm and nothing unusual occurred, Focha said.

The discovery was made as a correctional officer was waking the dorm’s 61 inmates at 4:50 a.m. An inmate announced that DePaz wasn’t stirring.

With help from inmates, DePaz was placed on the floor, and the officer, a sergeant and a jail nurse began emergency efforts to revive the man, who wasn’t breathing. They used an automated external defibrillator to attempt to restart his heart and gave him oxygen until emergency crews arrived, Focha said.

A Bells ambulance crew and Rincon Valley firefighters rushed to the North County Detention Facility, which is just off Airport Boulevard north of Santa Rosa, after getting a call at 4:56 a.m. about a code blue medical emergency at the jail, according to emergency dispatch records. DePaz was declared dead at 5:14 a.m.

During the incident, the dorm’s other inmates were moved to another dorm.

Staff Writer Elizabeth M. Cosin contributed to this story. You can reach Staff Writer Randi Rossmann at 521-5412 or randi.rossmann@pressdemocrat.com.