San Francisco police today identified a suspect in a murder in the city’s Nob Hill neighborhood over the weekend as 66-year-old Robert Graves. Officers were dispatched to an apartment complex in the 1100 block of Pacific Avenue at about 2:30 a.m. Saturday, police said. They arrived to find 24-year-old Geofrey Greer, of San Francisco, shot to death, according to police. Witnesses told investigators that the suspect and victim were involved in a dispute before the shooting, police said. Graves, a San Francisco resident, has been arrested in connection with the killing and has been booked into jail on suspicion of murder.