A district court on Monday apologized for a clerical error that resulted in the release from prison of Evan Ebel four years too soon and said it would review its practices to avoid another mistake.

Authorities have tied Ebel, 28, to the March 19 slaying of state prisons chief Tom Clements at his Monument home and the killing two days earlier of Denver pizza-delivery driver Nathan Leon.

Leon’s relatives said they appreciated the court’s acknowledgment of the error but found the words hollow.

“I was sick to the pit of my stomach. I would have preferred a public apology to me and my family,” Leon’s wife, Katie, said. “Obviously this was something that could have been prevented. My husband would still be here today. The father of my children would still be here today. Tom Clements would still be here today.”

The mistake allowed Ebel to be released from prison Jan. 28 without serving any additional time for a 2008 conviction for assaulting a prison guard, despite the terms of a plea agreement.

The April 2008 agreement called for Ebel to serve a prison term of four years — consecutively after completing an eight-year stint — for slipping out of handcuffs and punching the corrections officer Nov. 27, 2006.

Judge David M. Thorson announced the sentence at a June 2008 hearing but did not specify that it was to be served consecutively.

That led to prison officials imposing a sentence that was concurrent, meaning Ebel served no additional time for the conviction.

“Because the judge did not expressly state that the sentence was consecutive, the court judicial assistant did not include that term in the mittimus, the sentence order that went to the Department of Corrections,” 11th Judicial District Administrator Walter Blair wrote in a statement. “The court regrets this oversight and extends condolences to the families of Mr. Nathan Leon and Mr. Tom Clements.”

Prison officials are required to impose a concurrent sentence when a judge does not specify how it should be served, Department of Corrections spokeswoman Alison Morgan said. She declined to comment further.

Eleventh Judicial District Attorney Thom LeDoux said Monday he would consider reviewing other cases for similar mistakes, though he did not believe the problem was widespread.

Lane said her family was considering legal options. But local attorney Dan Recht said the families of the men who were killed will have no recourse as far as suing the 11th Judicial District because the court has immunity.

“The court has immunity from civil lawsuits from the actions it takes,” Recht said. “One of the most strongest entrenched immunities is for judicial officers.”

In addition to the clerical error, Ebel was released nearly four months early as a result of a 2011 law that allowed him and others to earn time off their sentences for their months and years spent in administrative segregation.

Ebel was shot to death during a gunfight with sheriff’s deputies in Wise County, Texas, where he crashed his 1991 Cadillac DeVille on March 21. Authorities have not said why he headed to Texas, but court records show that they found bomb-making materials, instructions and handwritten directions in his car. Neither the El Paso County Sheriff’s Office, which is investigating the Clements killing, nor Denver police would elaborate on the significance of those discoveries.

Stevie Marie Anne Vigil, 22, the Commerce City woman charged with illegally buying Ebel the 9mm Smith & Wesson handgun used in Clements’ death and the Texas shootout, has been released on $25,000 bond, her attorney said Monday. Court documents show that she bought the gun from a shop in Englewood between March 6 and March 13.

Attorney Normando Pacheco did not know how Vigil was able to post bond.

“All she said was family,” Pacheco said. He spoke with her briefly and “I told her to get some rest.”

Pacheco declined to comment on the specifics of the case but said Vigil’s release likely means she will not be entitled to a preliminary hearing that had been set for April 30.

Sadie Gurman: 303-954-1661, sgurman@denverpost.com or twitter.com/sgurman

Staff writer Carlos Illescas contributed to this report.