According to Kevin Keele, a private investigator hired by Shelley's family, and now a "48 Hours" consultant, Shelley Mook was last seen as she arrived at her ex-husband's house with their daughter, Lilli. What happened after that is a mystery.
"She's definitely not the type of person that would have left her daughter… if she had planned to leave, she would have definitely taken her daughter with her," Keele told "48 Hours."
Credit: Brittany Brooks
The morning after Shelley Mook was last seen, a car was discovered burning in a field not far from her ex-husband's home.
"Normally people wouldn't think it was a big deal… This is something that we deal with quite often," Rutherford County Fire and Rescue Chief Larry Farley told "48 Hours."
It was later discovered that the car belonged to Shelley, and it would be one of the few pieces of tangible evidence in her case.
Credit: Kevin Keele
Tyler Mook, Shelley's ex-husband, was the last person besides their daughter, Lilli, to see Shelley before she disappeared. He is on the record saying that she came over that afternoon and was upset about a potentially cheating boyfriend. He claims that Shelley and he made love, and afterwards she left to run some errands -- promising to be back later that night. According to Tyler, Shelley never returned.
Credit: Brenda Doneth
The Search for Shelley
Tyler Mook was questioned by police in 2011, but has never been arrested in connection with Shelley's case. He is, however, still a person of interest.
Anyone with information is asked to call the Tennessee Bureau of Investigation at 1-800-TBI-FIND [1-800-824-3463]
Credit: CBS News
Brittany Brooks, Shelley's best friend, says that she is skeptical of Tyler Mook. Brooks helped search for Shelley when she went missing, and continues to fight for justice for her friend. She claims that Tyler has never been very helpful in the search for Shelley.
Brooks told "48 Hours," "You have to wonder if you're not guilty why are you not out searching with us? Why are you not helping us?"
Credit: Brittany Brooks
Mook Pleads the Fifth
Shelley Mook had primary custody of Lilli when she disappeared. As a result, Tyler and Shelley's families began a heated court battle shortly thereafter -- each side claiming it was better suited to take care of Lilli.
Tyler, pictured here during a deposition in the case, was not always the most forthcoming. "In the deposition, he asserted his Fifth Amendment right against self-incrimination 140, 150 times plus," Kevin Keele told "48 Hours."
Kevin Keele, pictured here with CBS News correspondent Michelle Miller, was hired by Shelley Mook's family to investigate her disappearance and is still on the case.
Miller: Where are you taking me?
Keele: We are going to a cell tower in Beech Grove, Tennessee
Miller: A cell tower?
The cell tower Keele is referencing is the last one that pinged Shelley's cellphone the night she disappeared. He claims it was several hours after Shelley was last seen, and that he cannot image why she would be there.
Anyone with information is asked to call the Tennessee Bureau of Investigation: 1-800-TBI-FIND [1-800-824-3463]