 They surrounded the 14-story building, closed off local streets and posted sharpshooters on nearby rooftops.After searching his sister's second-floor apartment, police began a systematic canvass of all 312 units.At some point during the day, Mr. Davis forced his way at gunpoint into Apartment 14-EB, where Elroy and Sophia Sewer lived with their two daughters, just as neighbor Theresa Ali, and her 2-year-old son, arrived for a visit.