The body was found Thursday on Fox Island, southwest of Tacoma. The Pierce County medical examiner's office planned an autopsy Friday to determine the cause of death.
A ground search along the beach turned up no sign of the boy's mother, 29-year-old Shantina "Kat" Smiley of Silverdale, who disappeared with him on Saturday night. Divers on a boat searched as well and a Coast Guard helicopter and sheriff's office plane flew overhead.
That search may resume Friday, depending on weather, Troyer said.
Smiley's abandoned minivan, partially submerged with its doors open, was found Sunday on a remote Olympia-area beach about 12 miles south of Fox Island.
Thurston County authorities had been leading the search for the pair since the van was found in their jurisdiction.
It's not surprising that a body would travel that far in the water, said Thurston County sheriff's Lt. Chris Mealy.
"The Dana Passage goes right up that way," Mealy said, referring to a tidal system between Olympia and Tacoma. A wallet containing Smiley's driver's license, some cash and credit cards was found in the van.
Jay Carver, Azriel's father who flew here from Buffalo, N.Y., this week, went to the beach where the boy was found. Troyer said the father was not involved in identifying the body.
"You really don't know what you have in your life until they're gone," Carver told KING-TV. "It's a sad turn of events."
Two mismatched shoes, a partially full and corked wine bottle, an inhaler and an orange ball have washed ashore since the van was found.
Mealy said the items apparently belonged to the boy or his mother.
Smiley was heading from her home in Silverdale to her stepfather's house in southwest Washington when she and her son vanished Saturday night. Silverdale is about 16 miles west of Seattle, across Puget Sound.
Besides searching the area, investigators looked at phone records and talked to people who know Smiley or her son or may have met her Saturday night as she drove through the back roads of Washington state. Her fiance, Robb Simmons, told authorities she was a recovering alcoholic who had relapsed last week.
"We are grieving the loss of Azriel, and praying for Shantina. We are all severely hurting. We are getting the family together so we can grieve together, and so we can have some sort of peace right now," Simmons told the television station late Thursday.
He told The Associated Press he had no comment.
Mealy said there was no indication that a crime took place inside Smiley's 2005 Dodge Caravan.