Updated

The search for 13-year-old Ben Ownby on Thursday entered its fourth day, and police said there were no major breaks in the investigation into the boy's mysterious disappearance.

In spite of the growing stress, family members remained confident authorities would crack the case, said Ben's uncle, Loyd Bailie.

"I really think that we're going to have something here soon," Bailie said. "You've got county, state and federal and other jurisdictions on search teams. Everybody's gathering evidence and checking out leads."

Police confirmed Thursday that at least two people saw a suspicious white pickup truck that is the focus of an intense search for the straight-A Boy Scout. A neighbor saw the truck cruising Ownby's secluded rural neighborhood hours before his disappeared Monday, soon after getting off a school bus, said Franklin County Sheriff Gary Toelke.

A schoolmate saw the same truck speeding away moments after Ben disappeared from the subdivision near U.S. 50 in Beaufort, an unincorporated town about 60 miles southwest of St. Louis.

Neither witness could provide even a vague description of the driver, Toelke said at a morning news conference.

FBI profilers are drawing up a psychological description of the kind of person who might have abducted Ben. Toelke didn't know then the profile might be finished.

Between 20 and 50 volunteers were scheduled to arrive at the Ownby house Thursday to aid in the search. Friends, neighbors and strangers have been scouring the woods and passing out fliers since Monday.

William Ownby said the strain increases the longer his son is gone. He asked anyone who might be holding the boy to do the right thing.

"Drop him off somewhere where he can make a phone call," Ownby said.

Toelke said his office has received about 300 tips, many of them about white pickup trucks. Investigators are checking license plates against lists of registered sex offenders and interviewing truck owners about their whereabouts Monday.

The pickup had dents and rust and lacked hubcaps. The camper shell had one continuous window along the sides, with what appeared to be a ladder rack on top.

William Ownby was convinced his son was taken by "some stranger in the area."

Ownby said his son played computer games every day after school. Police took the family's computer Monday night and searched the hard drive to see if there was evidence that Ben met someone on the Internet who may have abducted him.

Both Ownby and Toelke said the search saw no evidence of an Internet acquaintance.

Toelke said police haven't searched computers at Ben's school, where he might have accessed the Internet, because they don't think the Internet played a significant role in the case.

Ben "played on the computer, but he wasn't really an Internet buff as far as we could tell," Toelke said.

Ben was last seen by a fellow student after the two boys got off the bus after attending middle school in nearby Union. The boys separated, and Ben's friend told authorities he looked back minutes later to see a white pickup truck with a camper shell in an apparent hurry, backing into a ditch briefly before speeding away.

The truck might have had the word "Nissan" written in black letters on the back, but authorities weren't certain it was a Nissan, Toelke said.

Ben is white, 4-foot-10 and weighs about 100 pounds. He was last seen wearing a hooded St. Louis Rams windbreaker and blue jeans.

Memories are still fresh in surrounding Franklin County of another high-profile kidnapping less than four months ago. Shannon Torrez of Lonedell is awaiting trial on charges she slashed the throat of a neighbor and stole the woman's infant daughter, Abigale Woods.

The baby was recovered days later when Torrez's sister-in-law contacted police.