Two convicted kidnappers killed a 63-year-old guard Tuesday during a failed attempt to escape from a Sioux Falls prison where they were serving lengthy sentences, authorities said.
Rodney Berget and Eric Robert, both 48, were apprehended on the grounds of the South Dakota Penitentiary, and a sweep of the facility showed all staff and inmates were accounted for, the state Department of Corrections said.
Berget is serving life for attempted murder and kidnapping convictions, and Robert is serving an 80-year sentence for a kidnapping conviction.
The duo tried to escape shortly before 11 a.m., assaulting the guard in the process, the Department of Corrections said.
Ronald Johnson, a corrections officer who worked at the penitentiary for more than 23 years, was pronounced dead at a hospital, and a second guard suffered minor injuries in the incident. The department did not release the second guard's identity or further details about the escape attempt or attack.
A woman who answered the phone at Johnson's home said the family had no comment.
The prison, which has both maximum and minimum security wings, was locked down pending an investigation.
Berget and Robert were taken to the county jail in Sioux Falls, authorities said.
South Dakota Attorney General Marty Jackley said Tuesday that the state Division of Criminal Investigation is investigating and more information would be released once the initial investigation and charging decisions are complete.
If the inmates are charged and convicted of murdering Johnson while trying to escape, prosecutors could seek the death penalty.
Gov. Dennis Daugaard said the state will act swiftly to bring the accused to justice and ensure the safety of prison staff.
"This incident is a somber reminder that our prison guards put themselves at risk, every day, to protect South Dakota from our worst criminals," Daugaard said in a statement.
Berget, of Aberdeen, was sentenced to life in prison after pleading guilty in December 2003 to one count of attempted first-degree murder and being a habitual criminal with prior felony convictions. He was accused of entering the home of his ex-girlfriend in Lead and shooting her and her boyfriend. Both survived.
Berget also was convicted in Meade County for kidnapping a convenience store clerk in Sturgis. He was arrested and the clerk escaped after troopers used road spikes to stop the car near Midland.
Berget had been in and out of South Dakota's prison system since 1984.
In 1987, he and five other inmates broke out of the penitentiary in Sioux Falls by cutting through bars in an auto shop. They took off on Memorial Day and Berget was not caught until mid-July.
The late Herm Solem, former prison warden, said in 2003 that he remembered Berget as the kind of inmate who could not stay out of trouble.
"He was always in some minor discipline problem, oftentimes being in the wrong place at the wrong time with the wrong people," Solem said.
Robert, of Piedmont, pleaded guilty to kidnapping in a 2005 plea bargain in which other charges were dismissed.
An 18-year-old woman told police that a man posing as a plainclothes police officer pulled over her car near Black Hawk, told her he needed to search it and then forced her into the trunk. She used her cell phone to call for help, and she was found unharmed.
The victim sued Robert in 2009 and was awarded more than $1 million in damages. Robert represented himself by telephone for that jury trial.
Associated Press writer Chet Brokaw in Pierre contributed to this story.