An error at a Colorado prison led to the early release of a white supremacist who is now suspected of killing Colorado’s prison chief.

According to ABC, Evan Spencer Ebel, 28, was released from prison on Jan. 28, four years ahead of his intended sentence due to a clerical error. Prison officials mistakenly believed that his two sentences were to be served at the same time rather than consecutively. As a result, Ebel walked free years early.

Just weeks later, Ebel was killed in a shootout with Texas police after a high-speed chase on March 21. Two days earlier, Tom Clements, executive director of the Colorado Department of Corrections, was killed with Ebel as the main suspect. Pizza delivery man Nathan Leon is also suspected to have been killed by Ebel.

In 2008, Ebel, a member of the white supremacist gang 211 Crew, agreed to a plea deal after he assaulted a prison guard at Freemont Correctional Facility. As a part of the deal, he was set to spend four more years in jail after the completion of an eight-year sentence for carjacking. After his 2005 sentence was completed, prison officials mistakenly let him go on parole.

"The judge announced a sentence of four years in the Department of Corrections but did not state it was consecutive because it was already required by the terms of the plea agreement," Walter Blair, the judicial district administrator for Colorado's 11th Judicial District, and Chief Judge Charles Barton said in a written apology.

"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," Blair wrote. "The court regrets this oversight and extends condolences to the families of Mr. Nathan Leon and Mr. Tom Clements."

After Ebel was released in January, he allegedly broke into Clements’ home and shot him to death. Two days later, he fled Colorado and was involved in a high speed chase with Texas police. Ebel was engaged in a shootout with police and later died in a hospital.

Police found the same gun used to kill Clements and Leon in Ebel’s car, as well as pizza delivery equipment believed to belong to Leon.

Reuters also notes that Ebel and the 211 Crew may have been involved in “targeted” slayings of Texas lawmen, including Kaufman County prosecutor Mark Hasse and Kaufman County District Attorney Mike McLelland and his wife, Cynthia. A group with similar leanings, the Aryan Brotherhood, is also suspected.

A search warrant affidavit stated McLelllands were found dead in their home Saturday evening by friends who had tried to reach them several times during the day, CNN reported Monday night. Each of them had been shot multiple times, the affidavit states.

A law enforcement source told CNN that investigators have recovered several shell casings from a .223-caliber rifle.