Authorities say that 49-year-old Genevieve Fay died Thursday after spending months in the hospital for pneumonia and a series of surgeries.
According to Bernalillo County Sheriff's deputies, Clarence Pergeson poured flammable liquid on Fay in June then lit her on fire. Authorities say Pergeson was upset that Fay no longer wanted to see him.
Charges against Pergeson changed Friday from attempted murder and aggravated arson to first-degree murder.
It was not known if he had an attorney.