Around 200 volunteers gathered in Parsons, about 100 miles west of Nashville, in an effort to locate missing nursing student Holly Bobo on Saturday.
The then 20-year-old disappeared in April of 2011 outside her Decatur County home.
Holly's brother reported to investigators he saw a man in camouflage lead her off into the woods behind their family's home.
"Agents [are] assigned to [the case] 24-hours a day. We follow up on everything we have. Yes, we are saddened it's not been solved, but very confident it will be," Decatur County Sheriff Roy Wyatt previously told Nashville's News 2.
Holly, now 21, is five foot, three inches tall and weighs 110 pounds.
She has blue eyes and shoulder-length blonde hair and was last seen wearing a pink shirt, blue jeans and black flip flops.
A $250,000 reward is being offered for her safe return.
Anyone with information regarding Holly's whereabouts is urged to contact the TBI at 1-800-TBI-FIND.