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The Tennessee Bureau of Investigation (TBI) confirmed new sightings and images Friday of missing 15-year-old Elizabeth Thomas and her 50-year-old abductor, Tad Cummins, who are being sought as part of an ongoing Amber Alert.

Cummins' wife, Jill, also publicly announced her intention to file for divorce.

"The filing of the divorce complaint is the first step to removing Jill from this situation. Jill will attempt to move forward with her life [as] this is a difficult time for her family," Jill Cummins' attorney, Michael Cox, said Friday.

Tad Cummins, a high school forensics teacher, allegedly kidnapped Thomas, a student at the school where he taught. The pair hasn't been seen since March 13.

"You know you can't hide forever... I know you are afraid and I know that a part of you is really sorry. It's not too late," Jill Cummins told NBC News as a message to her husband. "Your entire family's lives are a disaster right now because of this."

TBI reported on Friday that their investigators had obtained and confirmed surveillance images of Thomas with the former teacher at a Wal-Mart located in Oklahoma City on Thursday night. The sighting came via an anonymous tip reported on March 15.

Related: Tennessee Authorities Plead With Public in Search for Missing Teen

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The tip alleged that Cummins had used cash to purchase a myriad of food items, but stayed away from more expensive items.

Authorities said the images have indicated that Cummins has altered his appearance by darkening his hair, and that Thomas now has red hair, a change from her brownish-blonde hair. The bureau has begun efforts to determine what vehicle they are using.

Jill and Tad Cummins Courtesy of Jill Cummins

Thomas' father, Anthony Thomas, said people should "not be fooled by this disguise" with the hair color changes, and said the family wouldn't stop searching for them until his daughter is home safe.

"We now know with certainty that he took her. ... It was good to be able to see her face, finally. Every time I drive by Shoney's I think about how that was the last place she was seen alive," Anthony Thomas said in a statement. "It's so good to know she's out there. I feel confident with the help of law enforcement, the media and the public we will find them."

TBI suspects they are driving a silver Nissan Rogue with Tennessee tag TN 976-ZPT and have extended efforts to determine the pair's next destination.

Related: Teacher Who Allegedly Kidnapped Elizabeth Thomas Not in Video: TBI

More than 1,200 tips had funneled through the TBI as of Friday morning, according to the TBI.

Authorities have added Cummins to the state’s "Top 10 Most Wanted" list and are offering a $1,000 reward for verifiable information leading to his capture.

"We have, through the FBI, also shared with law enforcement in Mexico and Central America, relevant information about the case as well," said Josh DeVine, the TBI's spokesman.

Thomas is believed to have disappeared along with Cummins on Monday, March 13, from her school in Maury County, Tennessee. He was reported as pumping gas in the station nearby.

Tad Cummins, a former teacher, is believed to have kidnapped his 15-year-old former student. TBI

At the time of the abduction, the school district had already terminated Cummins' teaching contract amid ongoing investigations. He had allegedly been seen kissing Thomas at the school earlier in the year.

"Everything we had up until that point indicated that she more than likely went willingly," said Brent Cooper, a Tennessee attorney general.

However, authorities upheld the kidnapping statute and charged him with aggravated kidnapping once they learned that Cummins likely has two handguns. Given that information, they now consider the abduction to have been committed under coercion.

The TBI has also said that Cummins had been researching teen marriage over the past months and had watched television shows with the scenario.

Thomas' older brother released a video on Sunday, March 26, hoping others could use the video in recognizing her voice. The social media tag #bringelizabethhome is also being used.