First he told police he was at home on Sept. 28, 2010, when two men, a 21-year-old woman, and her 2-year-old son were marched up a Mattapan street and shot to death. Then, under withering interrogation, Dwayne Moore changed his story, telling Boston police detectives that he had been at the scene, but fled, and heard the shots from afar.

Moore, the 35-year-old charged in one of the worst killings in the city’s recent history, was inconsistent about his whereabouts that night during two interviews in the weeks following the murders. But in the 10 hours that he sat with two Boston homicide detectives, he was adamant about his innocence, at times begging police to believe him. At one point, he sank to the floor, sobbing.