JEFFERSON CITY, Mo. (AP) -- Two convicted murderers were missing from the state prison Thursday morning, several hours after an inmate who had killed his siblings was found dead in a prison work area.
Jefferson City police set up roadblocks outside the prison as part of the search for the missing inmates, but it wasn't immediately clear whether they had escaped.
About 200 prison officials were searching the penitentary grounds, which cover 47 acres with 25 buildings and numerous tunnels, Department of Corrections spokesman Tim Kniest said.
There were no confirmed sightings of the inmates outside the prison and no evidence to indicate an escape, Kniest said.
The two inmates, Chris Sims, 27, and Shannon Phillips, 35, have been missing since Wednesday night when the body of Toby Viles, 28, was found in the ice-making plant where the three men were working alone.
Sims was convicted of first-degree murder and armed criminal action and sentenced to life in prison for fatally shooting Gale Brown at a Shell service station on the 4900 block of Goodfellow in St. Louis on Sept. 25, 1997.
As part of their work, the inmates routinely used chisels and hammers to chop up ice. Guards do not directly supervise the workers but check on them periodically.
Viles was found with wounds to his head and neck and his death is being investigated as a homicide, Kniest said. Investigators were trying to determine the cause of death, as well as whether any of the icehouse tools were missing.
"We certainly are investigating the death as a homicide," Kniest said. "We don't have a motivation at this time."
Viles, who had been imprisoned since 1994, was 16 years old when he used a rifle to shoot his younger siblings -- brothers aged 3 and 11, and a 14-year-old sister. He was serving life without possibility of parole.
Sims has been in prison since 1998 on a life term for murder in St. Louis. Phillips was serving life without parole for a murder in Jackson County and had been imprisoned since 1996.
The Cole County sheriff's office, Jefferson City police and the Missouri State Highway Patrol were also assisting in the investigation and search.
The last time an inmate was killed at the Missouri State Penitentiary was February 1990, and it is also been more than a decade since someone escaped the prison, Kniest said.