His father, a gang member turned pastor, helped others turn their lives around. There were missions to Mexico, prayer sessions with former jail inmates and weekly Bible study gatherings. For Griego, there were jam sessions with the Calvary Albuquerque's youth band and pickup basketball games at the church.
That all changed last Saturday when his parents and three younger siblings were slain at home and Griego was arrested and charged with the killings.
On Friday, family and friends will gather at the church to mourn the deaths — a tragedy that just doesn't make sense to surviving family members or the church community that has watched him grow up.
Griego was just a normal teen to Vince Harrison, a former police officer who had known the family for about 10 years through his security work at the church.
"He did not fit the criteria of a kid who was crazy into guns and wanted to hurt people. That's absolutely false," Harrison said.
So how and why could something like this happen to a family like the Griegos?
The question is haunting family members and the church community as lawmakers across the country debate whether more gun control laws would keep another shooting from happening.
Public defender Jeff Buckels said Thursday that it's too early for anyone to rush to judgment about the teen's mental state, motives or plans. He said the Bernalillo County Sheriff's Department has been parceling out limited bits of what he described as "the most damaging supposed 'facts.'"
"This has led directly to a multitude of sensational headlines that threaten to finish Nehemiah's case in the public mind before it has fairly begun," Buckels said.
Sheriff Dan Houston described the case as "horrific" and said Thursday that he stood by the facts as presented in the investigation.
Detectives continue to pour over evidence gathered last weekend at the Griego home. They're also reviewing text messages and calls between Griego and his 12-year-old girlfriend and security video from Calvary, where the teen apparently spent much of the day following the early morning shootings.
He is facing murder and child abuse charges in the deaths of his family. They were all found shot to death inside their rural home south of Albuquerque last Saturday.
After the killings, authorities allege that Griego reloaded his parents' two semi-automatic rifles and put them in the family van and planned to gun down Wal-Mart shoppers. Houston has said investigators have no information that Griego actually went to a Wal-Mart that day.
The defense attorney promised he will consult with mental health experts and investigate the effects of violent video games. Authorities have said Griego liked to play "Modern Warfare" and "Grand Theft Auto."
"It's far too soon to know the meaning of this tragedy and far too soon to judge," Buckels said.
Since news of the shootings first hit Calvary last Sunday, churchgoers have been praying for the teen and the victims 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.
Friday's memorial service follows an hour-long prayer vigil that drew an estimated 2,000 people Wednesday night.
There were simply no signs, said Rick Zemke, a chaplain who knew the family and volunteered with Greg Griego at the Metropolitan Detention Center.
"They were always together. They just always seemed to click," he said. "It's hard to understand."