Jones was reported missing Tuesday afternoon, but had not been seen since 8:30 p.m. Monday, said Jim Bollinger of Marble Hill Search and Rescue.
Jones is a 5-foot tall, white male with a dark complexion. He weighs 90 pounds and was last seen wearing jeans, a dark-colored jacket and lime green shoes.
"He did not come to breakfast, and the mother told the other children to let him sleep," Bollinger said. "He hasn't eaten anything since last night."
Bollinger said this is the third time the boy has run away.
Sheriff's deputies from Bollinger, Cape Girardeau, Scott and Stoddard counties, highway patrol officers, two search-and-rescue dogs and volunteers on ATVs and on horseback searched the area around County Road 614, a mile west of Greenbrier. Bollinger said the dogs picked up a scent twice, but lost it.
Two highway patrol helicopters searched the area as well, and Tuesday night Bollinger said he was waiting for another helicopter with high-powered searchlights to arrive from Jefferson City, Mo., The Missouri Water Patrol was called in to search the Castor River area, Bollinger said. Authorities have gone door-to-door in and around Zalma searching for the boy.
"He has either wandered away pretty far and is lost, or he has fallen and he can't get up," Bollinger said.
Deputes searched the Jones' home inside and out and have been interviewing the other children in the home.
Brent is the adopted son of Mr. and Mrs. Roy Jones, who have had custody of him for eight years.
Southeast Missourian editor Bob Miller contributed to this report.