ALBUQUERQUE, N.M. — The New Mexico teenager accused of gunning down his family over the weekend had reloaded his guns after the attacks and planned to go to a Wal-Mart and randomly shoot people, authorities said Tuesday. Instead, 15-year-old Nehemiah Griego texted a picture of his dead mother to his 12-year-old girlfriend, then spent much of Saturday with the girl, they said. The two went to the church where his father had been a pastor, and Griego eventually admitted killing his parents and three younger siblings. Bernalillo County Sheriff Dan Houston said Griego had planned the attack for a week, …