Published: Apr 01, 2013 11:19 PM EDT

DENVER (AP) - Because of a paperwork error, the suspect in last month's killing of Colorado's corrections chief was freed from prison in January - four years earlier than authorities intended.
    
Judicial officials acknowledged Monday that Evan Spencer Ebel's previous felony conviction had been inaccurately recorded and his release was a mistake.
    
In 2008, Ebel pleaded guilty in rural Fremont County to assaulting a prison officer. In the plea deal, Ebel was to be sentenced to up to four additional years in prison, to be served after he completed the eight-year sentence that put him behind bars in 2005, according to a statement from Colorado's 11th Judicial District.
    
However, the judge did not say the sentence was meant to be "consecutive," or in addition to, Ebel's current one. So the court clerk recorded it as one to be served "concurrently," or at the same time. That's the information that went to the state prisons, the statement said.
    
So on Jan. 28, prisons officials saw that Ebel had finished his court-ordered sentence and released him. They said they had no way of knowing the plea deal was intended to keep Ebel behind bars for years longer.