Miller, 33, was found dead Oct. 17 in her Follett Street home. She was stabbed 34 times, primarily in the neck area.
Keys was quickly arrested and charged.
At a hearing Tuesday in Erie County Common Pleas Court Keyes pleaded guilty to murder.
Keys said little during the hearing other than he was sorry and wished he could take it back.
For reaction from family, police and prosecutors in Wednesday's Register. Click here for the ePaper, for home delivery or buy the Register daily at a newsstand near you.