OMAHA, Neb. (AP) — A former doctor has been found guilty of killing four people with ties to an Omaha medical school, including the 11-year-old son of a faculty member there.

A Douglas County jury convicted 42-year-old Anthony Garcia Wednesday of four counts of first-degree murder. He faces either life in prison or the death penalty.

Garcia, of Terre Haute, Indiana, was found guilty of fatally stabbing 11-year-old Thomas Hunter, son of Creighton University School of Medicine faculty member Dr. William Hunter; and the family’s housekeeper, 57-year-old Shirlee Sherman, in 2008.

He was also found guilty of the 2013 Mother’s Day deaths of another Creighton pathology doctor, Roger Brumback, and his wife, Mary.

Prosecutors say Garcia’s long-simmering rage over being fired from the medical school’s residency program in 2001 led him to seek revenge.