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DENVER — Authorities knew the ankle bracelet on parole Evan Ebel was tampered with  days before he allegedly killed pizza delivery driver Nathan Leon and state prisons chief Tom Clements, new documents show.

Ebel was released from prison on January 28, 2013 and was supposed to wear an ankle monitor. According to state documents, Ebel stopped reporting to his parole officer and his ankle bracelet signaled it was tampered with on March 14.

Authorities received the “tamper alert” at 1:54 p.m. that day. A parole officer tried to contact Ebel including visiting Ebel’s Commerce City home on March 19.

The officer determined Ebel was not there and notified the Colorado Parole Board and requested a warrant for his arrest on March 20. That was three days after Ebel had already allegedly killed Leon and one day after Clements was killed.

Ebel died on March 21, after a shootout with Texas authorities. He has been named as the main suspect in both the Clements and Leon murders.

Monday the DOC noted that because of a court error, Ebel was released from prison four years early. The judge in his trial failed to indicate at a sentencing hearing that Ebel should serve additional time in prison for a 2006 assault on a corrections officer.

Ebel had history of violence, but no clear motive in Clements death

FOX31 Denver has learned Ebel spent a great deal of time in prison and at one point threatened a security guard.

According to records from the Department of Corrections, Ebel first went to prison in February 2005 for an 11 year sentence on robbery and menacing charges out of Adams and Arapahoe counties.

In 2007, Ebel was given an additional 4 years in prison for an assault on a correctional officer.

All together, Ebel served 7 years, 11 months and 24 days in prison before he was released on January 28, 2013.  When he was released, Ebel was wearing an ankle bracelet when he was paroled.

Motive in Clements, Leon murder cases still unclear

No clear motive has emerged in either murder case.

But investigators said they are looking into all possible angles, including Ebel’s onetime membership in the 211 Crew — a white-supremacist prison gang.

Even as a teenager, Ebel’s behavior suggested he was interested in white supremacy, said Kurt Frey, who knew Ebel from a boot-camp-type program in Samoa.

Ebel got out of prison in late January after serving seven years — three for felony menacing, robbery and assault, another four for assaulting a guard. He spent five years of that time in solitary confinement.

It was his second stretch in prison, after doing one year of a three-year term for armed robbery.

Investigators are looking into whether Ebel might have conspired with other inmates to kill Clements.

CNN contributed to this report.