The Tennessee Bureau of Investigation said they have new leads to renew a search for a Shelbyville English teacher who went missing in March 2011. Shelley Mook, a mother of one child, has been missing for about a year and a half. Investigators said they searched the CSX rail yard in Cowan. The TBI said they are being assisted by about 10 other law enforcement agencies in the case. Shortly after her disappearance, Mook’s car was found burning in a field in Murfreesboro. Investigators believe she went to ex-husband Tyler Mook’s home to drop off their daughter. The TBI said their main suspect all along has been Mook’s ex-husband. They said he has been uncooperative throughout the investigation. Police said he was the last person who saw her. He reported her missing, but not until the day after the car was found. Although he is the main focus, but the TBI is not ruling out the possibility that someone else was involved. 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 1-800-TBI-FIND.