Colorado Springs (CNN) -- Days after he led police in a wild car chase that ended in a hail of gunfire, authorities are investigating the driver's links to two Colorado killings. And whether he has ties to a third shooting, in Texas, earlier this year.
Suspect Evan Spencer Ebel, 28, was fatally shot in the head Thursday after he opened fire on the deputies chasing him in in Montague County, Texas.
Investigators have found evidence linking him to the slaying of a Colorado prison chief and a pizza delivery driver this week.
And the FBI is looking for possible evidence linking the January slaying of Kaufman County prosecutor Mark Hasse to Tuesday's killing of Colorado prison chief Tom Clements at a Denver suburb.
"This is part of routine investigative work when two crimes occur under somewhat similar circumstances," the Kaufman County Sheriffs Office said in a statement Friday. " If any link is found, or a possible link is disproven, that information will be released at the appropriate time."
In an affidavit, Texas authorities detailed what they believe links him to the prison chief's killing.
Of key focus in the affidavit is a 1991 black Cadillac authorities say the suspect was driving in a wild, high-speed chase Thursday. He opened fire on sheriff's deputies before slamming into an 18-wheeler, climbing out of the wreckage and opening fire again.
Witnesses reported a similar vehicle -- a black, boxy car with Colorado license plates -- near the prison chief's house the day he was killed.
Among the links in the cases, according to the affidavit, are shell casings from a 9mm handgun found at Clements house. They are the same brand and caliber used in the shooting of James Boyd, a Wise County, Texas, sheriff's deputy who tried to pull over the suspect.
Pizza box carrier
Boyd, who had on a bullet-proof vest, managed to call for help and tell law enforcement which way Ebel was driving. The deputy remains hospitalized at a Dallas-Fort Worth area hospital.
During the investigation into the shooting, authorities found a Domino's Pizza box carrier and a uniform jacket in the trunk of the Cadillac, prompting Denver authorities to go to Texas to examine the car.
They are investigating the killing of Nathan Collin Leon, 27, a Domino's Pizza deliveryman in Denver. Leon disappeared from work Sunday and was found dead in the Denver suburb of Golden.
Denver investigators said there is a "strong connection" between Leon and Clements killings, but have said little about a possible motive.
Did Ebel kill a pizza deliveryman to get a hold of his uniform as part of an effort to disguise himself? Did he target Clements because of the prison chief's crackdown on white supremacist gangs in prison? Was he part of a wider conspiracy to kill Clements? Or was it something else?
Investigators looking into Clements' killing have told reporters they are considering numerous angles.
One is that Ebel, a former member of the 211s -- a white-supremacist prison gang -- might have conspired with other inmates to kill Clements, the Colorado, sheriff's department said.
Clements earned widespread recognition for prison reforms and crackdown on prison gangs, including the 211s.
Citing media coverage of the shooting and its possible connection with the the 211s, authorities locked down Colorado's prisons on Friday.
History of violence
Ebel lengthy prison record dates to his teen years, including a 2003 charge for felony armed robbery after he brandished a gun and threatened to kill a man unless he handed over his wallet, court documents show. He was 18 at the time.
He pleaded guilty and was sentenced to three years in prison, serving just over a year.
Just months after his release, he was arrested again. This time for felony menacing, robbery and assault. He pleaded guilty to those charges in 2005 and was sentenced to another three years in prison.
In 2006, while in prison, Ebel was charged with assaulting a detention officer, records show. He pleaded guilty and received an additional four years on his sentence.
Ebel served his entire sentence and was given mandatory parole on January 28, 2013, according to the state Department of Corrections.
CNN's Jim Spellman reported from Colorado and Ed Lavandera from Texas, and Chelsea J. Carter reported and wrote from Atlanta. CNN's Ashley Fantz and Drew Griffin contributed to this report.