Clement Sander confirmed to CBS News that the body was that of his granddaughter, Emily.
Investigators refused to give details about the state of the body or how it was found. Police Chief Tom Boren said the cause of death was not yet
known. An autopsy is planned.
Sander, 18, was last seen leaving a bar with a man who has been the focus of a nationwide search since police found large quantities of blood in a Kansas motel room where he was staying.
Investigators have not yet found a link between a missing college student and her activities as an online porn star named Zoey Zane, but publicity about her explicit photos has brought a flood of tips, many of them false leads.
Before she vanished, nude photos of Sander appeared on various Web sites. The national publicity surrounding her double life kept phones ringing continuously at the El Dorado police station.
"No tips were generated from it," Boren said.
The police chief said the publicity was unlikely to help.
"We did talk to the lady that operates the site. We didn't find any viable connection with this main suspect at this point," he said.
Sander, who attended Butler Community College, was last seen Friday leaving the bar with Israel Mireles, 24. Authorities are looking for him and his 16-year-old pregnant girlfriend.
The rental car Mireles was driving was found abandoned Tuesday in Vernon, Texas, where he has relatives. Investigators interviewed family members and planned to bring the vehicle back to Kansas for processing.
"We feel they know where he is at, but they haven't shared that with us," Boren said.
On Thursday, searchers on foot and all-terrain vehicles were checking the tall grass along each side of Highway 54 near Neal, Kan., as they traced the route Mireles may have taken Saturday on the way to Baxter Springs to pick up his girlfriend.
So far searches using dogs, planes, underwater equipment and divers at the Walnut River dam have yielded no new evidence.
"We have about exhausted a lot of the resources we have until we can focus on a particular area," Boren said.
Dozens of people gathered Wednesday in El Dorado for a candlelight vigil for Sander. The turnout moved her grandfather, who said Emily's disappearance shows tragedy can suddenly strike anyone.
"All I can say to you young folks out there is be careful," Clement Sander said. "It is a cruel world."