BOISE, Idaho -

Authorities are investigating the death of an Ada County Jail inmate who they say apparently took his own life.

KTVB-TV reports  that the sheriff's office says the 40-year-old Garden City man was found unresponsive and not breathing in his cell Saturday night. Deputies administered CPR and called for medical help, but paramedics were unable to revive him.

Sheriff's officials say deputies had checked on the man, who was housed alone, about 25 minutes before he was found unresponsive in his bed.

Investigators say evidence suggests a self-inflicted injury caused the man's death.

The inmate, who has not yet been identified, was booked into jail on July 9 for a delivery of a controlled substance charge. He was being held on $50,000 bond.