Inset: Carly Gregg (Mississippi Department of Corrections). Background: Gregg using her phone in the kitchen after gunshots heard inside home (Law&Crime).

Defense attorneys representing infamous matricidal teenage girl, Carly Gregg, 15, say their client deserves a new trial because she was previously treated for hearing voices using horse therapy.

"On Wednesday, September 26th, 2024, a reporter for Fox 40/WLBT informed defense counsel that Kevin Gregg, Carly's biological father, had given an interview, part of which would be aired later that night," the motion for a new trial reads. "In an unaired portion of his interview, Kevin Gregg disclosed that Carly was placed in equestrian therapy as a young child due to experiencing auditory hallucinations."

The claim made in the motion, however, has been sharply disputed by the media organization referenced in the court document.

Here's how the Jackson, Mississippi-based Fox affiliate reported on that aspect of the new trial motion late Friday:

Todd alleges Gregg admitted to placing his daughter in equestrian therapy because she was hearing voices.

But a thorough review of the transcript of that interview and the reporters who worked on the story reveal Carly's father never said anything about that.

In response to the confusion, Gregg's lead attorney, Bridget Todd, said another member of the defense team, Kevin Camp, was the conduit for the information -- and that a "female reporter" with the local Fox affiliate told him what Kevin Gregg said earlier this week.

"I've been discussing getting the B-Roll interview with WLBT's lawyer all day today, specifically regarding that disclosure," Todd told Law&Crime in an email on Friday. "No one has denied it to me."

Equestrian therapy, also known as equine therapy, can be helpful to people suffering various forms of trauma, including emotional trauma, according to the Mayo Clinic.

Despite the she-said, he-said, she-said, he-said nature of Carly Gregg's earlier-in-life history with therapy, the mere fact of such a history, if true, would be highly relevant to previous defense claims, the motion for a new trial argues.

"This new information supports Dr. Clark's diagnosis of unspecified schizophrenic disorder and is likely to lead to a different result at a new trial," the filing reads, "As such, Carly is entitled to a new trial."

On the third day of Gregg's week-long trial, the defense called psychiatrist Andrew Clark, who diagnosed the girl with Bipolar II disorder -- but only after the shootings.

Clark repeatedly testified that in his professional opinion, Gregg did not appreciate the difference between right and wrong when she shot and killed her mother, Ashley Smylie, 40, and tried to kill her stepfather, Heath Smylie, 39, at their home in Brandon on March 19 -- when she was still 14 years old.

More Law&Crime coverage: Chilling kitchen camera video shows 14-year-old girl casually using phone just moments after mom's screams and 3 gunshots could be heard from bedroom

In sum, the medical professional argued the girl was under-diagnosed and had unsuccessfully switched mental health medications a week before the violence, which only made things worse.

In any given motion for a new trial, timing is also relevant.

Carly Gregg's attorneys say they did not have the new mental health information about their client until well after the trial, despite their "reasonable diligence" to obtain such information -- due to Kevin Gregg completely eschewing any role in his daughter's case.

"Kevin Gregg has never cooperated with his daughter's defense, nor did he attend any of Carly's pretrial hearings, or a single day of her week long trial," Todd told Law&Crime. "Kevin Camp called the number he got for Kevin Gregg immediately regarding his statements to the media. Mr. Gregg has not returned his phone call."

The motion for a new trial details the extent of defense efforts to contact the girls father -- and his non-involvement:

Defense counsel contacted the attorney representing Ashley Smylie in her civil proceedings against Kevin Gregg regarding documentation or information that might be helpful in Carly's criminal trial. However, no such documentation was identified or produced. Kevin Gregg refused to cooperate in Carly's defense, refused to talk to the State, refused to talk to the mental health professionals evaluating Carly, and refused to come to any pretrial hearings or a single day of Carly's criminal trial.

The new trial motion is not limited to the horse therapy issue. Rather, the 9-page document contains a laundry list of various legal arguments for a new trial and complaint regarding alleged misconduct by the trial court and prosecutors.

"[W]itnesses necessary to establish Carly's defense were improperly excluded from testifying at the trial," the motion argues. "[W]itnesses were improperly restricted in the testimony they could provide in Carly's defense ... Carly did not receive a fair and impartial trial."

Now, a circuit court will rule on those claims.

On Sept. 20, a Rankin County jury found Gregg guilty of murder in the first degree, attempted murder, and evidence tampering. Hours later, she was sentenced to life in prison without the possibility of parole.