text: U.S. boy , 13 , accused of murdering adoptive mother . DALLAS 1996-08-26 A 13-year-old Dallas boy has been charged with murdering his adoptive mother over the weekend , police said on Monday . Margaret McCullough , 55 , was found dead in her home on Saturday with gunshot wounds to the head . Police , who at first thought her son had been kidnapped , found him on Sunday with a friend in his mother 's car in Oklahoma and arrested him . A shotgun and a .357 handgun were found in the car . A police spokesman said the boy was being questioned . " They are talking to him now about the motive and everything else . " McCullough had adopted the boy , who was the grandson of her late husband , shortly after his birth but neighbours said they often had loud arguments .