Tuesday marks one year since Shelbyville teacher Shelley Mook was last seen.
The 25-year-old has been missing since she left Harris Middle School around 3 p.m. on Monday, February 28, 2011.
Investigators believe she went to her ex-husband's home to drop off their daughter.
It is believed that her ex, Tyler Mook, was the last person to see the young mother alive.
Mook was supposed to meet a maintenance man at her new apartment in Murfreesboro after dropping off her daughter, but never made it.
Her car was found burned out in Rutherford County later that night.
Now, one year later, very little evidence has been found on Mook's whereabouts.
Bill Pietkiewicz is the assistant principal at Shelbyville Central High School and the former principal at Harris Middle School.
"We had no idea [Shelley] would still be missing at this point," he told Nashville's News 2 Monday.
Mook's absence has been felt at the school since the day she was reported missing.
"It's very much like a member of your family that's gone," Pietkiewicz continued
The Tennessee Bureau of Investigation is continuing with the investigation, and is currently relying on the public's help for information.
"It just takes that one piece of evidence or that one tip or lead or break in the case to be able to solve this," TBI spokesperson Kristin Helm told Nashville's News 2.
She said Tyler Mook is still considered a person of interest.
"[Tyler Mook] is still very much a person of interest. He has never really cooperated with our agents as far as sitting down and giving them an interview about the last time he saw her," Helm said.
According to a Facebook page dedicated to finding Shelley, Mook's mother now has custody of her little girl, and she is living in Pennsylvania.
A family spokesperson told Nashville's News 2, "Everyday we hold out hope that the person responsible will be held accountable."
A vigil marking the one year anniversary will be held in Shelley Mook's hometown of Erie on Tuesday at 7 p.m.
Anyone with information on Mook's whereabouts should call the Bedford County Sheriff's Department at 931-684-3232, the Rutherford County Sheriff's Department at 615-904-3049 or the Tennessee Bureau of Investigation at 615-744-4000.