A 65-year-old Ukiah man headed toward a possible life prison term was found dead in his bunk at the Mendocino County Jail on Friday morning, authorities said.

Scott Joseph Smith was unresponsive when corrections personnel found him shortly before 8 a.m. during regular morning rounds, Mendocino County Sheriff's Lt. John Bednar said.

Smith had been scheduled for sentencing later in the day on a recent third-strike conviction that was to put him in prison for 25 years to life, a spokesman for the Mendocino County District Attorney's Office said.

A Vietnam War vet with a history of mental illness, drug use, psychiatric commitments and violent crimes, he had been in custody since Feb. 4, when he was arrested for assault on a peace officer while wielding an ax and urging the officer to "shoot me, shoot me," according to court records relayed by District Attorney's spokesman Mike Geniella.

Smith's July conviction on the assault and another charge for failure to appear in court follow previous convictions for assault with a deadly weapon and battery with serious bodily injuries.

Both were strikes under the state's "Three Strikes, You're Out" law, setting Smith up for 25 years to life on his most recent conviction, Geniella said. Smith had been sharing a cell at the Mendocino County Jail with three other inmates, though none apparently noticed anything amiss, Bednar said. Jail personnel were the first to realize he was not breathing, Bednar said.

There were no obvious signs of foul play or suicide, authorities said. Smith had a history of cancer and was reportedly in poor health, Geniella said.

Sheriff's personnel and the District Attorney's Office will investigate, the sheriff's office said.