Police arrested 43-year-old Michael D. Purnell at his home Wednesday night after being called earlier that day to the home of 70-year-old Dorothy Gudger.
Troopers were called to Gudger's home after neighbors concerned about her welfare entered the house and found her dead on the floor.
Investigators subsequently learned that Purnell had recently been seen doing odd jobs for Gudger, and that he was a registered sex offender.
Police said they believe Gudger was killed Monday night.
Purnell is being held without bail on charges of rape, murder, burglary and possession of a deadly weapon during the commission of a felony.