Early today, we spotted a listing on the King County Jail Register indicating that someone was booked last night for “investigation of homicide.” We checked this morning with Seattle Police to see if by chance it was related to one of the unsolved murders in West Seattle — and Detective Jeff Kappel from the media unit has just called us back with confirmation, so you’re hearing it here first: The 21-year-old man who’s in jail is being held in connection with the Friday night killing of a 71-year-old woman in the Sharon Lynn Apartments at Fauntleroy/Dawson (first reported here Saturday morning as a “suspicious death”). He says the suspect “is a family member, so it’s a domestic-violence homicide” and was arrested yesterday afternoon, about 8 hours before being booked into jail. That’s all the information available right now; the victim has not yet been publicly identified, and investigators have not yet described the manner in which she was killed. ADDED 9:27 PM: Police have now posted this on SPDBlotter (no additional details beyond what we’ve written).