"Unfortunately, they came up empty-handed," Tennessee Bureau of Investigation spokesperson Kristin Helm said this morning.
"They didn't find anything," Bedford County Sheriff Randall Boyce said today. Several of his detectives were involved in the search, he said.
"Special agents of the TBI have recently received information that led them to search the CSX train yard in Cowan," Helm said.
She did not disclose specifics, but Boyce said he heard that an employee of the train yard had "smelled something" around the time Mook went missing.
WSMV-TV reported Thursday that Mook's ex-husband, Tyler Mook, had worked for CSX Railroad at the Cowan yard.
Tyler Mook has been considered a "person of interest" in the case since his ex-wife's disappearance, investigators say. Several of his relatives live in Franklin County.
Mook's lawyer has consistently refused comment.
The search, led by the Tennessee Bureau of Investigation, lasted from 8:30 a.m. to 1 p.m. and spread out from a command post at the train yard, Helm said Thursday.
Mountainous areas of the county, including Keith Springs Mountain, were also searched, according to investigators.
The Bedford County detectives, Bedford County Fire Department and Bedford County Emergency Management Agency were joined by the CSX Railroad Police, Franklin County Sheriff's Department, Cowan police, Franklin County EMA, Maury County EMA and Search and Rescue and the Tennessee Emergency Management Agency.
Shelley Mook, a reading teacher at Harris Middle School, was last seen on the afternoon of Feb. 28, 2011, at Tyler Mook's home outside Shelbyville as she dropped off their daughter on her way to Murfreesboro, where she was to meet a maintenance man at an apartment complex. Her burned car was found that night near Murfreesboro.
A $20,000 reward remains in effect for information in the case. Call the Bedford County Sheriff's Department, (931) 684-3232; or the Tennessee Bureau of Investigation, (800) TBI-FIND.