ALBUQUERQUE, N.M. - The New Mexico teenager accused of gunning down five family members over the weekend ambushed his father as he returned home from an overnight shift at a rescue mission, then reloaded his rifles 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 and her family, authorities said. That evening, he went to the church where Griego's father had been a pastor, and Griego eventually confessed to killing his parents and three younger siblings.
"The motive, as articulated by the suspect, was purely that he was frustrated with his mother," Bernalillo County Sheriff Dan Houston said. "He did not give any further explanation."
Houston said Griego had planned the shootings for at least a week, but it's unclear if he ever actually went to a Wal-Mart or why he changed his mind about continuing the attack, which occurred the same day thousands of gun advocates gathered peacefully at state capitals around the country to rally against stricter limits on firearms. The "Guns Across America" events were being held just after President Barack Obama unveiled a sweeping package of federal gun-control proposals.
Griego told detectives he also contemplated killing his girlfriend's parents, Houston said.
The sheriff said he didn't know if Griego's contact with his girlfriend avoided further bloodshed. But he said she apparently knew what had happened, and officials are investigating whether she should be charged with failing to report the crime.
"We know Nehemiah had been contemplating this for some time," Houston told reporters at a Tuesday news conference. Griego apparently had told others of his plans, but whom and when was still under investigation, Houston said.
The teen waived his right to arraignment in adult court Tuesday on charges of murder and child abuse resulting in death and a judge ordered him held without bond. He was arrested Saturday at his family's home in a rural area southwest of Albuquerque.
The sheriff's office identified the victims as Greg Griego, 51, his wife, Sarah Griego, 40, and three of their children: a 9-year-old boy, Zephania Griego, and daughters Jael Griego, 5, and Angelina Griego, 2. All appeared to have gunshot wounds to the head.
According to Houston and charging documents, it all began early Saturday at the family's home, when Nehemiah Griego - angry and annoyed with his mother - acted on what he described to investigators as homicidal and suicidal thoughts.