Shawn Adkins, 25, told The Associated Press he would "never ever do anything to harm Hailey" Dunn, whose mother reported her missing Dec. 28 in Colorado City, a 4,500-resident town about 240 miles west of Dallas. Adkins was then the live-in boyfriend of Billie Dunn, Hailey's mother.
Adkins said he prays daily for Hailey's safe return.
Billie Dunn told police that Adkins said he last saw the teen Dec. 27. According to police, Dunn said Adkins told her Hailey said she was walking to her father's home nearby and then to a friend's house where she was spending the night. The middle school cheerleader did not arrive at either location.
Colorado City's city manager, Pete Kampfer, said Friday that Adkins still is among several people of interest in the investigation but declined to offer details about any others. No one has been arrested in the case.
Kampfer, who is serving as Colorado City's police spokesman on the case, said several law enforcement agencies are actively searching for the teen, including police, the Texas Rangers and FBI.
"They assure me they check out every lead," Billie Dunn told the AP on Friday. "They're not just looking at him (Adkins). Anything could have happened.
"But I don't feel like they're getting anywhere with anything," she said. "It's been 18 days."
Dunn has denied any involvement in her daughter's disappearance. She said she asked Adkins to move out of their home Jan. 5.
"When I asked him to leave the house, he was just crying a lot, saying `You know me. You know I love you and David,"' Hailey's 16-year-old brother, Dunn said. "'You know that I would never hurt you."'
Dunn said Friday she had not exchanged text messages with Adkins in a few days.
Adkins told the AP he loves Hailey and that his life has been "flipped upside down" since her disappearance.
"I struggle so hard just to make it through the day," he said. "I can't begin to imagine what Hailey's family, especially her parents and brother are going through."
Adkins said police have misquoted him in affidavits.
In one, police said Adkins at first was "very positive" about Hailey, but that as time went on he indicated she was promiscuous and used drugs. Adkins denied that Friday. He said he had told police Billie and Hailey Dunn had discussed birth control and that he had told investigators the teen was "boy crazy."
Her father, Clint Dunn, has said Hailey is popular, isn't into boys or drugs and "she's just a good ol' American girl."
Another affidavit said police disputed Adkins' assertion that he went straight to visit his mother in Big Spring, some 40 miles west of Colorado City, after he left work at 6:10 a.m. on Dec. 27. Police said cell phone records indicated he had been in Colorado City between 6:35 a.m. and 6:56 a.m. On Friday he again said he had gone straight to his mother's house that day.
More than 100 billboards featuring Hailey's picture, information about the case and a law enforcement phone number have been set up along interstates in West Texas and elsewhere. The girl is described as white, 5-foot-1, 120 pounds, with hazel eyes and brown hair with blondish streaks.
Dunn said it's been a difficult time.
"I don't know whether she's safe, I don't know whether she's hurt," Dunn said. "I don't know if she's somewhere wondering 'Why hasn't my mom found me?' That's the hardest.
She said she also wanted people to know her daughter is more than "the cheerleader," noting Hailey also plays volleyball, basketball and softball and is a first chair saxophone player in the school band.