"There was a human error," Sheriff Marc Richards told reporters at a news conference. "Twenty-eight years, we all make mistakes, and that was a mistake."
Richards said, however, that neither he nor Deputy Daryl Evans, who was tasked with transporting three inmates to Augusta State Medical Prison, knew of Andre Maurice Jackson's history of violence.
"I was not aware of the circumstances at that time," Richards said.
Jackson, 30, whose nickname is "Poncho," has been charged in the June 29 slaying of L.V. Wilson, 38, whose body was found in 1900 block of Haynie Drive in Augusta.
He also was charged in the July 2 death of Janee Jquanda Johnson, who was found stabbed in her apartment in the 800 block of Spruce Street.
Investigators in Richmond County are still looking into whether Jackson might have been involved in other area homicides, but they would not say which ones.
Jackson had served three years of a five-year sentence at Lee State Prison in Leesburg, Ga., for theft by extortion when he was released on parole in July 2009. His parole was revoked when deputies in Richmond County charged him with the murder of Wilson.
With drug convictions dating back to 1999, Jackson is someone they should have known more about, Richards acknowledged.
Jackson and two other inmates were being taken to Augusta State Medical Prison on Tuesday to await transfer to other state prison facilities.
Jackson had been taken to Taliaferro County last week for a court date involving an April 2010 arrest on DUI and marijuana possession charges, the sheriff said.
He had been in the Wilkes County jail -- where the Taliaferro County Sheriff's Office houses all its inmates -- awaiting transportation to Augusta.
About 3 a.m. Tuesday, Evans parked the unmarked Chevrolet Tahoe he was driving at a Waffle House in Thomson to buy breakfast for the three inmates.
Leaving them alone inside the sport utility vehicle, the deputy forgot to remove the keys from the ignition when he walked inside.
A few seconds later, two of the inmates -- identified as Johosephis Pierce, 32, and Bradford Reid, 29 -- went into the restaurant and said Jackson had told them to get out or go with him.
"Just as soon as he got to the cash register, he turned around, he looked and the inmates were coming in the door and the Tahoe was leaving," Richards said.
Stopping to buy food is not usual procedure, but "it happens," the sheriff said.
There was no barrier between the inmates and the deputy inside the SUV, the sheriff said. Although secured with handcuffs and leg-irons, Jackson had managed to get into the driver's seat and take off, the sheriff said.
Columbia and Richmond County deputies chased him, at one point deflating three of his tires with stop sticks. Still, Jackson continued to drive until crashing at Barton Chapel Road and Frankie Industrial Boulevard.
He got out of the SUV and ran but was soon captured.
In response to questions about his department's procedures -- including the lack of a barrier to prevent the inmates from entering the front seat and the absence of an additional guard -- Richards said budget cutbacks have hobbled his small department.
He said he is considering disciplinary action against the deputy, in addition to a review of procedures on inmate transfers.
Jackson is now charged with fleeing and attempting to elude an officer, reckless driving and obstruction of an officer, according to Richmond County jail records.
He also faces charges of escape and motor vehicle theft in McDuffie County, Richmond County sheriff's Lt. Robbie Silas said.