By Zelie Pollon
ALBUQUERQUE, New Mexico (Reuters) - A 15-year-old accused of killing his parents and three younger siblings over the weekend planned to continue his rampage at a local Wal-Mart store then die in a shootout with police, investigators said on Tuesday.
Bernalillo County Sheriff Dan Houston told reporters that 15-year-old Nehemiah Griego, who is accused of shooting his mother and siblings before killing his father hours later, had been contemplating the killing spree for "at least a week."
After killing members of his family, Griego told police, he reloaded and planned to go to a nearby Wal-Mart store.
"He contemplated ending this with mass destruction," Houston told reporters Tuesday.
Instead, the teen went to his girlfriend's home and then to a church where his father once worked as a pastor.
A staff member called the police, Houston said.
The murders have convulsed the faith community of Albuquerque, where Greg Griego, the teen's father and a former gang member, worked as a pastor and volunteered with inmates at the Metropolitan Detention Center.
A Statement of Probable Cause described Griego's changing stories to police as well as the gory details of the quintuple homicide that took place on Saturday inside the family's Albuquerque home.
The teen told police he shot his mother, the first victim in his rampage, because he was "frustrated" with her, Houston said.
After shooting his brother and two sisters, Griego, who police said often played violent video games, then waited five hours for his father to return from work and ambushed him with an AR-15 assault rifle - the same type of weapon used in the Sandy Hook, Connecticut, elementary school shootings.
"It's the first time I've been to a crime scene with so much destruction in one home," Houston said, describing the scene at the family home as "horrific."
Police said that after the killings, Griego sent his 12-year-old girlfriend a picture of his mother's body and the two then spent the day together, possibly planning to kill her parents.
The dead have been identified as 51-year-old Greg Griego, his 40-year-old wife Sarah Griego, and three of their children: a 9-year-old boy and two girls, ages five and two.
Griego will make his first court appearance later on Tuesday and will be charged with five counts of murder and three counts of abuse of a child, said Kayla Anderson, a spokesperson for Albuquerque's District Attorney's office.
Charges may also be brought against the boy's girlfriend, Houston said. He told reporters that Griego showed no evidence of abuse or use of drugs or alcohol, and showed no signs of remorse.
"He was shocked that he was being arrested," Houston said.
The couple had 10 children, with several of the older siblings from a former marriage.
"Greg was dedicated to providing a good, godly home for himself and his kids," said long-time friend Steve Stucker. "It's very shocking for all of us who knew him."
(Editing by James B. Kelleher, Cynthia Johnston and Jim Marshall)