Boy, 12, to Face Charges in Parents' Killing

VIDEO: Frito Lay truck driver and his wife found murdered in their home.
WATCH 12-Year-Old Held after Parents Murder

The uncle of a 12-year-old Colorado boy suspected of killing his parents and severely wounding two siblings said the horrific event has left family and friends struggling to understand what went wrong.

"It's a mystery to me," said Wally Long. "I'm sure it's a mystery to everyone. I don't know if anyone can explain it at this point and maybe never will be able to explain it."

Wally Long is the older brother of Charles Long, who was found dead along with his wife, Marilyn Long, Tuesday night in their Burlington, Colo., home. The police who found them were responding to a 911 call in which the caller said three people in the house had been shot.

Two other siblings, a 9-year-old boy and 5-year-old girl, were wounded in the attack and were recovering in a Denver hospital.

The couple's 12-year old son, who police said made the 911 call, was taken into custody.

A prosecutor plans on filing first-degree murder and other charges by the end of Friday. District Attorney Robert Watson said he has not decided whether he will charge the boy as an adult.

Wally Long has spoken with friends and family close to the murdered couple, and even with the benefit of hindsight, he insisted nobody recalled any red flags that might have foreshadowed the alleged crimes.

"In all my time talking with my brother, I never got anything from him," Wally Long told ABC News. "I never personally saw any indication. I've talked with his brothers and sisters. Nothing that we can think of that was an indication of what was going on."

Wally Long insisted his brother and sister-in-law were not abusive parents. As far as he knew, Long said, his 12-year-old nephew had not been diagnosed with any medical problems such as depression, was not taking medications and had never been in trouble with police.

Documents in the case so far have been sealed, and investigators have released few details about what might have driven the 12-year-old to kill.

"He's a typical kid, probably liked to play and video games, that kind of thing," Wally Long said. "I can't imagine what would have happened, what went through his mind."

Uncle Wally Long Expects Seriously Wounded Niece, Nephew to Recover

Doctors have told Wally Long that his wounded niece and nephew should completely recover from their wounds while confirming grisly details about their injuries. The young girl had stab wounds to her back and neck.

"The girl is speaking to us, interacting with us, and laughing," Long said.

The 9-year old boy sustained gunshot wounds, he said, and also was stabbed in the genital area.

"There was some injury there, but it's been fixed," Long said. "That's what I've been told."

Long said his brother and sister-in-law were deeply religious and home schooled their children, but rejected the idea that home schooling had made the children socially isolated.

"There are exceptions but, by-and-large, home schooled children are often better socialized because they spend more time with adults and mixed ages," said Long, himself an advocate of home schooling.

"My brother and his wife loved their kids tremendously; the kids were their life," Long said. "Their lives were wrapped around those kids. Home schooling is not an easy choice, but they were committed to that for their children."

He's had no contact with his accused nephew yet, and does not yet know when he might see him. He does not have an opinion on whether the boy should be charged as an adult or a juvenile.

"I think my question would be, 'How are you right now?" Long said. "I would be concerned for him, I guess. He is still who he is. He's still my nephew."