A black Cadillac, bullet casings and a pizza box appear to connect a parolee with ties to a white supremacist prison gang to the shooting death of Colorado's prisons chief, according to a search warrant affidavit obtained Friday by CNN.

The affidavit, filed by the Texas Department of Public Safety's Ranger Division, details what authorities believe links Evan Spencer Ebel, who died in a shootout with sheriff's deputies in Texas, and the Colorado killing of state prisons chief Tom Clements.

Of key focus in the affidavit is a 1991 black Cadillac that authorities say Ebel was driving in a wild, high-speed chase Thursday that saw the 28-year-old open fire on sheriff's deputies before slamming into an 18-wheeler, climbing out of the wreckage and opening fire again.

Hours later, Ebel died from a gunshot wound to head suffered during the shootout, leaving behind more questions than answers in a case that has spanned two states.

On Friday, the wreckage of the Cadillac was under intense scrutiny after witnesses reported a similar vehicle -- a black, boxy car with Colorado license plates -- near the Monument, Colorado, house of Clements on Tuesday, 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 a Wise County, Texas, sheriff's deputy, it said.

In the Cadillac's trunk was a Domino's Pizza box carrier and a Dominos uniform jacket, it said.

That pizza carrier and jacket are a key reason why Denver authorities are also in Texas to examine the Cadillac.

They are investigating the killing of 27-year-old Nathan Collin Leon, a Domino's Pizza deliveryman in Denver.

Leon disappeared from work on Sunday and was found dead in the Denver suburb of Golden. Leon's family said he delivered pizzas as a way to earn extra money for his wife and his three girls.

Denver investigators tell CNN there is a "strong connection" between the killings of Leon and Clements.

Even as the investigation appears to link Ebel to the shooting, authorities 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?

High-speed chase in Texas

This much is known: On Thursday, Ebel sped through Montague County, Texas, near the Oklahoma state line, about 700 miles from Monument.

Deputy James Boyd tried to pull the car over. It's unclear exactly why, other than it would have a been a routine part of Boyd's job.

Boyd did not know about the Clements case, authorities said.

Ebel shot the deputy three times, hitting him twice in the chest and grazing his head. Wearing a bulletproof vest, the deputy managed to call for help and to tell law enforcement which way Ebel was driving. Authorities say they have looked at the dashcam video of the shooting.

Boyd remains hospitalized at a Dallas-Fort Worth area hospital.

The information the deputy gave allowed law enforcement to catch up with Ebel.