Prosecutors say neighbors saw Michael Spaulding stabbing 67-year old Virginia Spaulding.
It happened on the landing of their apartment on Monday.
They say he went inside to change clothes, then stabbed her several more times before leaving.
Investigators say he stole her purse and car and was arrested later as he was trying to steal wine coolers from a bowling alley.
Spaulding is being held without bail in the hospital wing at Cook County Jail.