Charlie and Braden Powell were killed by their father, Josh Powell. Their mother, Susan Powell, remains missing.
Susan Powell's father, Chuck Cox, was overwhelmed with emotions as the memorial was erected on Monday.
"It's great. Finally," he said. "Good to see it coming together finally."
"This has been a long time," said his wife, Judy Cox.
The two watched as crane operators set in place the angel made of thousands of pounds of granite.
"And something good from it will happen," said Judy Cox.
Charlie and Braden Powell have been laid to rest at a hillside dedicated to children. Also buried at the hillside is Sebastian Hizey, who lost his life after being struck by flying debris at a monster truck show.
"It's hope for everybody," said Judy Cox. "This is not just for the boys; it's for all the kids. Every one is special."
After the boys' death, there was concern that Josh Powell was going to be buried next to his boys. But Crime Stoppers purchased the nearby plot, preventing that from happening. That effort grew into the hillside for children and $50,0000 in donations for the monument..
Inscription on the statue, called "Angel of Hope", says it is "dedicated as a place of love and healing for all those who have suffered the loss of a child."
The Coxes are still suffering the loss of their beloved child, Susan Powell.
"Our daughter is still missing, and we want to know where she is," Chuck Cox said.
But they say at least they know where their grandsons are -- now being watched over by an angel.
The memorial will be dedicated Thursday at 7 p.m. at Woodbine Cemetery in Puyallup. The date marks the third anniversary of Susan Powell's disappearance from her Utah home.