Chuck Cox stands in the bedroom of his two grandchildren who died Sunday in a murder-suicide plot investigators say was planned well before a home explosion Sunday afternoon. (97.3 KIRO FM/Brandi Kruse)

Chuck Cox walked into the bedroom he had set up for his two young grandsons, Braden and Charlie Powell. The room is large and bright, with plenty of windows. It's mostly empty, except for two small beds and a rocking chair.

The bed closest to the door is covered in a Disney Cars bedspread for five-year-old Braden.

"He liked Cars and his favorite color is orange," Chuck said. "This was a quilt made for him," he added, smoothing his hand over a blanket on the bed.

Braden slept next to his older brother, seven-year-old Charlie, who had a Spiderman-themed set. The room brings back a flood of memories for Chuck Cox.

"I saw them last Saturday night just curled up on the beds, with the blankets, sleeping peacefully," he said. Cox plans to remove the beds from the home now that the boys are gone, saying it is too painful to see them.

Chuck and his wife Judy Cox spoke to the media Monday for the first time since their grandsons were murdered during a fiery explosion at their father's rental home in Graham Sunday. They called Josh Powell's actions "cowardly" and "desperate."

"He murdered the grandchildren, two innocent grandchildren," said Mr. Cox. "I don't know what he did to my daughter. I don't know how, but I know he's responsible for her being gone."

Powell had been a person of interest in his wife Susan Powell's disappearance since she vanished from their Utah home in Dec. 2009. After fighting to gain custody last year, the Cox family thought the boys would finally be safe.

"We suspected that if he had the boys in his control, with him, living with him, and he felt the police were closing in on him, that he was capable of killing the children," Mr. Cox said to reporters outside his house. "But we thought we were safe because we had the children and his visits were supervised."

But when a social worker brought the boys to their father's home for a scheduled visit Sunday, Powell let the boys in then blocked the social worker from entering. She called her supervisors to report that she could smell gas, and seconds later the home exploded.

The Pierce County Medical Examiner said late Monday that the boys had also been struck in the head and neck with a hatchet before succumbing to carbon monoxide poisoning during the blaze.

"We were hoping to at least give the boys a chance at a good life," said Mr. Cox. "And that has been taken away by their father killing them."

Now, Chuck and Judy Cox can only look forward. They say they will find closure only when they get answers about their daughter's disappearance.

You might also be interested in:

Nation reacts to Powell murder-suicide
David Boze: The selfishness of Josh Powell
Dave Ross: The law is just one more helpless bystander
A reporter's perspective: Powell home a 'haunting' scene
Josh Powell sent multiple emails before explosion
Could Washington have done more to protect Powell boys?
Images: Community gathers to remember Powell children
Classmates in Puyallup grieve loss of Charlie Powell
Police: Josh Powell intentionally killed two sons in house explosion

MyNorthwest.com, Staff report

You might also be interested in:

• Police: Josh Powell doused entire house with gasoline
• Photos: Chuck and Judy Cox's home Puyallup home