COWAN, TN (WSMV) -
It's been 18 months since Shelley Mook was last seen, but new developments in the case had search crews back out in Franklin County on Thursday looking for the missing mother and teacher.
Mook, a Shelbyville English teacher, has been missing for about a year and a half, and in that time the Tennessee Bureau of Investigation has named her ex-husband as their prime suspect in her disappearance.
Shortly after her disappearance, Mook's car was found burning in a field in Murfreesboro.
The TBI wouldn't disclose what prompted the new search, but about 10 other law enforcement agencies joined the TBI in searching a CSX rail yard in Cowan, TN.
Family and friends said the fact search crews were out again was a hopeful sign.
"I just hope it opens people's eyes to know this is not ended. It is not going to stop until we find what happened," said friend Brittany Brooks.
At this point, investigators are looking for a body, and family and friends said they are looking for closure and justice.
"I hope that nobody ever thinks that after two years or three years if we don't find anything that it will be over, because it won't until something is found and until somebody is found responsible," Brooks said.
Channel 4 News has confirmed Mook's ex-husband's brother worked for CSX, the company that owns the tracks and area where workers searched, but the TBI isn't elaborating on any possible connection.
A former coworker said Tyler Mook was fired from his job back in December. That coworker said no one she knows has seen or heard from him since then.
Channel 4 contacted Tyler Mook's attorney Thursday to see if they had anything to say about the newest search, but the only comment was "no comment."