ALBUQUERQUE, N.M. (AP) -- 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, but it's unclear if he ever actually went to a Wal-Mart or why he changed his mind. The teen said he had planned to randomly shoot more people, then die in a shootout with law enforcement, according to authorities.
Griego told detectives he also contemplated killing his girlfriend's parents, Houston said at a news conference.
The teen was set to appear in adult court Tuesday on charges of murder and child abuse resulting in death. He was arrested Saturday at his family's home in a rural area southwest of Albuquerque.
It wasn't immediately clear if Griego's contact with his girlfriend avoided further bloodshed. But a statement of probable cause says Griego spent time at the church, first talking to his girlfriend and her grandmother and then meeting with the church pastor and a security guard.
Church officials called authorities, and Griego initially told arriving officers he had come home Saturday morning after spending time at a friend's house to discover his family dead.
The teen later confessed to shooting his mother because he "had anger issues" and was annoyed with her, the charging document said. He said he killed his siblings after they woke up and became upset, then grabbed his parents' assault rifle and waited in the downstairs bathroom to ambush his father.
After killing his father, Griego said he reloaded the guns so "he could drive to a populated area to murder more people," according to the statement.
His plan, the statement said, was to "shoot people at random and eventually be killed while exchanging gunfire with law enforcement."
Detectives spent two days collecting evidence and trying to piece together what led to the attacks, which occurred on 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.
"There's no other way to say it, except that we have a horrific crime scene down there that we are working on," Bernalillo County Sheriff Dan Houston said Sunday.
The detectives had finished their work at the home by Monday afternoon. The metal gate at the home's entrance was shut, a small bouquet of purple flowers was on the top of the gate, and at each side there were religious signs, including one that read "Jesus is the reason for the season."
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.
A sheriff's detective questioned the teen Saturday night, and the details of their conversation were spelled out in the statement.
The teen allegedly told the detective that he took a .22-caliber rifle from his parents' closet around midnight Saturday and shot his mother in the head while his younger brother slept next to her.
Griego told the detective that his brother woke up but did not believe him that their mother was dead, so he showed his mother's bloody face to his brother and then shot him, according to the statement.
The teen is accused of then shooting his two young sisters after they began crying in their room, and retrieving a military-style semi-automatic rifle from his parents' closet and waiting in a downstairs bathroom for his father to come home. The statement said he shot his father multiple times after he passed the bathroom doorway.
Greg Griego was a pastor who had once served at Calvary, one of Albuquerque's largest Christian churches. He also was well-known throughout the law enforcement community for his work as a voluntary chaplain.
A records check by the Children, Youth and Families Department indicated no problems with the Griego family and that Nehemiah Griego had never been in trouble with the law.
Sheriff's Deputy Aaron Williamson confirmed there was no history of any emergency calls to the home in the recent past.