The 13-year-old girl was last seen at her Colorado City home last December.
Peter Hyatt, who hosts an internet radio show, said this week: "I believe Billie Jean Dunn caught her daughter, Hailey, in a sexual act with Shawn Adkins and tempers exploded resulting in injury and eventual death to Hailey."
Adkins is Billie Dunn's former live-in boyfriend and a suspect in the case.
"He's absolutely horrible at what he does and he's no good at his job, because everything he's ever said has been a lie," Dunn said.
Dunn's lawyer, John Young, called Hyatt's words outlandish.
"(He said things) that only a fool would say, but certainly things that may, if I have my way, land this fellow in a court in Mitchell County, Texas," Young said.
A decision on whether or not to take Hyatt to court has not yet been made.
There have been few clues as to what happened to Hailey, and law enforcement has remained tight-lipped about the case.