A 17-year-old high school senior from South Bend, Ind., helping his grandfather pick up litter in an Eastern Washington farm field, briefly thought he’d picked up a melted piece of plastic PVC piping.

But a second look by Brenton Pavel convinced him he was holding a human skull, one his 73-year-old grandfather, Arnold Hudlow, thought probably was that of a child.

The discovery Aug. 12 on the farm 10 miles north of Connell, near a county access road paralleling U.S. Highway 395, prompted an initial search by Adams County sheriff’s deputies.

A larger search by an FBI evidence recovery team Thursday and Friday turned up a few additional bones, but some of them may be those of animals, authorities say.

A visit to the scene Tuesday showed evidence that a backhoe apparently had been used to dig up an area in the search for more remains.

Adams County Sheriff Doug Barger confirmed on Monday that human bones were discovered, but he continued to decline to say on Tuesday that the remains include a skull.

Sheriff’s deputies were packaging the bone pieces and would be driving them this week to Seattle for a scientific examination by forensic anthropologist Kathy Taylor of the King County Medical Examiner’s Office, Barger said.

He said it was too early to conclude the remains were those of a child, and he avoided speculating whether they could be those of 11-year-old Cody Haynes or 5-year-old Sofia L. Juarez.

Cody Haynes disappeared from his Kittitas home – about 88 miles away from where the bones were discovered – in September 2004 after being disciplined by his parents. They claimed he was a runaway. Other children in the Haynes household have been taken into state custody.

Sofia Juarez vanished in February 2003 after being given $1 and allowed to leave her Kennewick home – about 52 miles from where the bones were found – to go to a convenience store.

The sheriff said he doesn’t want to raise false hopes that the remains are those of either missing child. The FBI has been involved in both disappearances.

The Kittitas County search and rescue team was involved in the search of about 100 acres surrounding the spot where the skull was found.

“They could be anything,” the sheriff said of the bones. “They could be a child; they could be an adult. They could be modern; they could be ancient.”

But Brenton Pavel’s mother, Cindy Pavel, said her son and others who saw the remains were convinced it was a human skull and possibly likely that of a child because of its size.

Cindy Pavel said her family flew from Indiana to Spokane on Aug. 3 for an annual family gathering at the farm home of the family patriarch, Arnold Hudlow, who lives near Connell.

“The first day Brenton got there he got to go fight a range fire with his grandpa,” she recalled.

Then on Aug. 12, the grandfather gathered up Brenton and another grandson for another tradition that’s become part of the family gathering: cleaning up garbage at the edge of fields, along access roads. With grandpa behind the wheel of a pickup, the teenage boys rode on the tailgate and pitched garbage in the back.

Brenton’s mother learned about the discovery when her son returned to his grandfather’s home and went straight to the bathroom sink to wash his hands.

“Grandpa came in and he said, ‘Brenton’s got a story to tell,’ ” Cindy Pavel recalled Tuesday when reached at her home in South Bend.

“Brenton said, ‘Yeah, I picked up this thing that looked like melted PVC.’ Then he said, ‘Oh, my gosh, this isn’t PVC. It’s two pieces that fit together and it’s a skull.’ That’s when he yelled, ‘Grandpa!’ ” Cindy Pavel said.

Her son put the pieces of skull back on the ground, close to the spot where it had been spotted, she said. Upon returning to the family home, Hudlow called the Sheriff’s Department.

The bones were found on what farmers call “CRP land” – land that is planted in grass and taken out of wheat production. In July, waist-high grass and weeds were burned off in a wildfire accidentally started by a passing car.

“If it had not burned off, we would not have spotted the skull, that’s for sure,” Hudlow said Tuesday.