Missing Tennessee teen's father seeks to depose witnesses in hopes of finding daughter

— -- The father of a Tennessee teenager who was allegedly kidnapped by her former teacher filed a petition in court Thursday, asking to depose witnesses who may know more about their purported relationship.

Authorities believe 15-year-old Elizabeth Thomas may have been abducted by Tad Cummins, 50, who is wanted on allegations of aggravated kidnapping and sexual contact with a minor.

The court filing is asking for witnesses who may have any information that could aid authorities in their search for Elizabeth to be deposed.

"The family cannot simply wait for information to trickle in," Jason Whatley, the attorney representing Anthony Thomas, Elizabeth's father, told ABC News on Thursday. "This petition will hopefully bring a fresh light into the disappearance of Elizabeth."

The legal move comes more than three weeks after Elizabeth was reported missing on March 13.

The only confirmed sighting of the pair was at a Walmart in Oklahoma City, Oklahoma, two days after the pair disappeared. The Tennessee Bureau of Investigation said that Cummins, who was fired one day after the alleged kidnapping, "may have been abusing his role as a teacher to groom [the teen] ... in an effort to lure and potentially sexually exploit her."

One of Elizabeth's schoolmates reported seeing her and Cummins kiss in his classroom on Jan. 23, according to a school district investigative report, but both denied the claim. A Maury County School District investigative report from January reads that neither one "admitted to behaving inappropriately towards the other."

Although the district said it couldn't confirm the alleged kiss happened, the report said Elizabeth would be removed from Cummins' class and she should be "instructed to bring anxiety issues to the school administration and guidance counselors."

The report also said "Cummins will be reprimanded in regards to his duty to uphold his professional responsibility and behavior as a teacher."

A subsequent letter from the district to Cummins on Feb. 3 stated that Elizabeth was in the teacher's classroom that day, which the letter said violated a previous order by the district.

Three days later, on Feb 6., the district wrote a letter to Cummins telling him he was suspended without pay immediately "pending an investigation."

The petition filed in court Thursday and obtained by ABC News states that Elizabeth "began feeling guilty" for his suspension from school and that Cummins allegedly "played upon this guilt."

"Moreover, evidence has surfaced that [Elizabeth] became fearful of Cummins' reaction to his suspension and her belief that he would punish her in some way for it," the petition stated.

According to the court filing, Elizabeth's father had learned information from various sources, including her siblings and friends, that show "a continuous pattern of grooming by Cummins" of the teen "for months," leading up to her alleged abduction. The petition states that Cummins told Elizabeth that, because of the kissing incident, "her future collegiate and work career was ruined, thus causing her to believe that her best option was to leave with him."

The petition states that Cummins had on more than one occasion picked up the teen from her house for a meal, unbeknownst to Elizabeth's father, "threatening her that if she did not go with him she would face repercussions at school."

According to the court filing, Elizabeth "had told various siblings and/or friends that she was scared of Cummins and that she felt 'in over her head.'"

Elizabeth's father asserts in the petition that Cummins was "stalking" his daughter. After his suspension from school, Cummins would frequent the fast food restaurant where Elizabeth worked, the petition stated. Elizabeth's father was informed that she had "at times hidden in the restaurant from Cummins and asked employees to lie about her presence at work, not desiring to see or speak with him, and showing fear of him," according to the court filing.

Elizabeth's father believes "Cummins preyed upon the child for months on end, nudging and molding her until her will to resist was conflicted and ultimately broken," according to the court filing.

"She is for all purposes a victim of a masterfully manipulating predator," the petition stated.

Whatley, the attorney for the teen's father, told ABC News on Thursday that the family believes there are classmates, friends and teachers who may know more information that could help in the search for Elizabeth, but added that he feels some people may be intimidated or scared to talk to authorities.

Whatley added in a statement that the "process of this investigation has been frustrating" for the Thomas family.

"Perhaps the most concerning element has been the hesitancy of some persons to fully cooperate in sharing information that they know," Whatley said Thursday.

"The purpose of our petition as filed today will hopefully put an end to that hesitancy displayed by some and will help us, as the family, to methodically confirm facts that have been at times unclear," he continued. "We have brought this petition for no purpose except to provide a vehicle for gathering information."

Authorities are asking that anyone with information call 1-800-TBI-FIND and that anyone who sees a car with Tennessee license plate number 976-ZPT call 911.