ROOSEVELT — Nassau County investigators said a man killed his girlfriend outside her East Raymond Avenue residence Friday before returning home and taking his own life. According to police, the 37-year-old man fatally stabbed the 33-year-old woman after an argument along the path of the Nassau Road intersection. The man then headed back to his home on Union Place where he stabbed himself to death, authorities said. According to investigators, the couple had a history of domestic violence with an order of protection in place.