The evidence appears to be mounting that a Colorado prison parolee, killed in a shootout this week in Texas, may have been involved in the brazen murder of the head of Colorado's prison system. NBC's Kristen Dahlgren reports.

Colorado Governor John Hickenlooper, a longtime family friend of a prime suspect in the shooting death of the state's prisons chief, said on Sunday that the now-dead suspect always seemed to suffer from a "streak of cruelty and anger."

Colo. Dept. Of Corrections / AP This undated photo released by the Colorado Department of Corrections shows paroled inmate Evan Spencer Ebel.

Hickenlooper said he and Jack Ebel, the father of white supremacist ex-convict Evan Ebel, had been friends for more than 30 years and that he had spoken to him since the 28-year-old parolee from Denver emerged as a lead suspect in the shooting last Tuesday of Tom Clements, executive director of the Colorado Department of Corrections.

"From the beginning, his son just seemed to have this bad streak, a streak of cruelty and anger," Hickenlooper told CNN's "State of the Union."

"They did everything they could," he said. "They worked with Evan again and again but to no avail. He had a bad, bad streak."

Evan Ebel was killed by police on Thursday after a high-speed chase through Decatur, Texas. He is also a suspect in the killing of pizza delivery man Nathan Leon in Denver, police there have said.

Hickenlooper said an investigation is continuing and that "all the signs" in the Clements killing seemed to point to Ebel, whom he confirmed had been connected to a prison-based white supremacist group.

"We can't see clearly what a motive was," he added.

The governor, who said his own personal security had been beefed up recent days, did not rule out the possibility that the Clements killing had been ordered by jailed white supremacist gang leaders targeting public officials from behind bars.

Lieutenant Jeff Kramer, a spokesman for the sheriff's office in El Paso County, Colorado, said on Sunday that Evan Ebel was definitely considered a suspect in the death of Clements, 58, who was shot on Tuesday when he answered the door at his home about 45 miles south of Denver.

Shell casings found at Clements' home were the same brand and caliber of the Hornady 9-mm bullets Ebel fired at Texas police, according to the search warrant filed in Texas for police to search Ebel's Cadillac.

"We're still waiting for the results of some ballistics testing that we're doing up here in Colorado ... to see if the gun used in Texas is the same gun used in the Tom Clements homicide case," Kramer said.

Ebel was a member of a white supremacist prison gang, the 211 Crew, and had been paroled in the Denver area, a law enforcement official said.

Authorities have said they were looking for ties between the death of Clements and the January killing of Mark Hasse, a prosecutor in the Kaufman County District Attorney's Office. Kaufman County is east of Dallas.