Judge W. Brent West accepted Ellenwood's guilty plea and scheduled sentencing for June 10. Prosecutors said Odle's family members plan to speak at the sentencing.
Odle was sexually assaulted and badly beaten inside her room at an assisted living home the night of May 3, 1993.
An employee told police she heard faint cries for help coming from Odle's room. When the employee opened the door, a man ran out, down the hallway and out of the building, according to an affidavit for an arrest warrant.
Odle died six days after the brutal attack.
But it took over twenty years for police to link DNA evidence to Ellenwood, who was arrested at his home in Alaska last May.
At a January preliminary hearing, prosecutors laid out much of the DNA evidence that placed Ellenwood at Odle's residence, located near 24th Street and Adams Avenue including that Ellenwood's fingerprints were found on Odle's window, that his DNA was on clothing left behind in Odle's apartment, and that his DNA was linked to a sexual assault of a 57-year-old woman that happened hours later just blocks away.
Prosecutors allege that Ellenwood stabbed the 57-year-old woman, who was walking near 23rd Street and Washington Boulevard, with a letter opener that he had taken from Odle's apartment. That woman told police that a man had stabbed her, then told her to lie down in some nearby bushes. She complied, and he subsequently raped her.
Ogden Police Detective Richard Childress testified at the preliminary hearing that a DNA match in the second rape case didn't come until October 2012, when the match tied Ellenwood whose DNA profile was taken while he was incarcerated at an Idaho prison from 2002 to 2008 for an aggravated assault conviction to the second crime scene.
The detective testified that the match was made only recently because DNA testing has become more sensitive as science and technology improved over the years.
Childress said that when he went to Haines, Alaska last May to arrest Ellenwood, he questioned him in a holding cell, where the suspect denied ever being at the assisted living home and denied any involvement in either sexual assault case.
Ellenwood was returned to Utah in July, and is being held without bail at the Weber County jail.