Amber Alert
This representational picture shows police officers stop an Amber Alert vehicle on a freeway ramp in Santee, California, Dec. 11, 2014. Reuters/Mike Blake

Search for missing teen student Elizabeth Thomas suspected of being kidnapped by her teacher Tad Cummins continued after Tennessee law enforcement officials discredited reported sighting of the pair in Memphis, Tennessee. An Amber Alert for Elizabeth was issued after she went missing on March 13.

Tennessee Bureau of Investigation (TBI) tweeted Thursday saying they were looking into the reported sighting of 15-year-old Elizabeth and 50-year-old Cummins in Memphis suburb of Collierville in Shelby County. The county sheriff’s spokesman told NBC News that Cummins was positively identified in surveillance video recorded at a Shell gas station in the city at 1:30 p.m. EDT.

Read: New Details Emerge On Tennessee Teacher Suspected Of Kidnapping Teen Elizabeth Thomas

However, TBI spokesman Josh DeVine posted an update on Twitter saying the reported sighting was a false alarm.

Cummins worked as a health science teacher at Maury County’s Culleoka Unit School, where Elizabeth studied. After the teen disappeared, law enforcement officials said they suspected Cummins to be behind her kidnapping. He is now on Tennessee’s “Top 10 Most Wanted” list and TBI issued a warrant against him for kidnapping and having sexual contact with the minor. He was also fired from his job following the alleged kidnapping.

There have been reports of romance between the student-teacher duo and District Attorney Brent Cooper told People magazine Monday that Cummins exchanged “romantic” and “troubling” emails with Elizabeth.

“You could describe it as somewhat intimate in nature,” Cooper told People, adding the emails were “not a conversation expected for a teacher to be having with a 15-year-old student.”

The district attorney also said Cummins sent those messages to Elizabeth through his work email, which do not contain anything “really graphic or explicit, but definitely inappropriate.” He added the emails do not “make clear that anything physical had happened between them, but it definitely makes clear that the nature of their relationship, they seemed to view as romantic.”

However, TBI Director Mark Gwyn said Tuesday the alleged relationship between Elizabeth and Cummins was not “romance.”

"She is 15, a child. He is 50, a grown man. She's a high school freshman. He's a former teacher. This is, and was, not a romance," Gwyn said. "This was manipulation solely to benefit Tad Cummins. This is not a fairy tale. This is a case of kidnapping."

Also on Tuesday, TBI said the officials suspected the missing student and teacher are likely to have gone to Mexico. The bureau also tweeted a Spanish translation of Elizabeth's missing poster Wednesday.