FIRST ON FOX: The lawyer for slain travel blogger Gabby Petito’s parents has requested phone records from AT&T regarding her suspected killer Brian Laundrie and his parents from the second half of 2021.

Petito’s parents, Joseph Petito and Nichole Schmidt, have accused the Laundries of knowing that their son murdered his former fiancée and traveling partner -- and of being aware of the location of her remains but refusing to speak.

The family’s Florida attorney Pat Reilly is seeking "copies of all phone bills and phone records to include lists of phone calls made, text messages exchanged, the substance of text messages, for the time period July 2, 2021 through November 23, 2021 for any numbers for Christopher Laundrie, Roberta Laundrie or Brian Laundrie," according to a new court filing.

Petito and Laundrie set off on their cross-country "van life" tour of national and state parks in her Ford Transit van in early June of that year. Their first major stop came at Monument Rocks in Kansas on July. 4.

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Gabbpy Petito looks to the right

Gabby Petito poses for a photo on Instagram. (Instagram)

The records could potentially shed new light on what the Laundries were discussing before and after the slaying, and whether their son admitted to the crime.

"[It’s] all part of the discovery process," Steve Bertolino, one of the Laundries’ lawyers, told Fox News Digital regarding the AT&T subpoena Thursday. "We already gave him all the information we had in our possession."

Read the court filing (App users go here):

Last month, Petito and Schmidt’s attorney alleged that Roberta Laundrie offered to lend her son a shovel following the slaying — while her legal team says it was written before the couple left on their road trip.

The relationship appeared to sour months into the trip, and police in Utah responded to a report of domestic violence alleging that Laundrie hit Petito outside an organic grocer in Moab on Aug. 12. There were no arrests, but officers split the couple up for the night.

She last spoke with her mother on the phone on Aug. 25.

Christopher and Roberta Laundrie outside AT&T store

Christopher and Roberta Laundrie leave a Florida AT&T store on Oct. 19, 2021.

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On Sept. 19, an FBI-led search found her remains in the Bridger-Teton National Forest, north of Jackson, Wyoming.

The couple had camped there weeks earlier. Teton County Coroner Dr. Brent Blue soon determined she had died of homicide by manual strangulation, and the FBI later revealed she also suffered blunt-force trauma to the head.

On Oct. 20, Fox News Digital was present in the Myakkahatchee Creek Environmental Park when Laundrie’s parents found a dry bag and other personal items belonging to the couple.

Brian Laundrie's parents, Chris and Roberta Laundrie are seen outside their home

Brian Laundrie's parents, Chris and Roberta Laundrie are seen outside their home in Sarasota County, Florida on Wednesday, October 19, 2022, ahead of the one year anniversary of Brian being found dead in a Florida swamp. Chris is carrying Panera Bread bags while Roberta carries a Radio Flyer jigsaw puzzle. Roberta wears a crocheted blanket over her shoulders. (Mark Sims for Fox News Digital)

The park, just 10 minutes from their home in North Port, is where law enforcement found his remains that same morning. The FBI confirmed his identity the following day.

According to investigators, he shot himself in the head and left behind a confession, which they recovered from his bag.

"I ended her life," one passage reads. "I thought it was merciful, that it is what she wanted, but I see now all the mistakes I made. I panicked. I was in shock."

Map of Gabby Petito's road trip

A map showing the route Gabby Petito and Brian Laundrie took during their 2021 road trip, which ended in a murder suicide. (Fox News, Google Maps)

Laundrie wrote that he killed Petito after he claimed she injured herself when she fell in Wyoming. He also wrote: "From the moment I decided, took away her pain, I knew I couldn't go on without her."

Her parents’ lawsuit alleges that his parents knew about the slaying shortly after her disappearance, while police were still treating it as a missing person case.

Chris and Roberta Laundrie at Myakkahatchee

Chris and Roberta Laundrie in the  Myakkahatchee Creek Environmental Park on the morning police discovered their son's skeletal remains. (Michael Ruiz/Fox News Digital)

The lawsuit focuses on the statement that Bertolino released on the Laundries’ behalf on Sept. 14, 2021, as searches were taking place for Petito. It also accuses the Laundries of going on a family camping trip in early September despite knowing that she had been killed and the location of her remains.

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The trip took place after Laundrie arrived at his parents’ Florida doorstep in Petito’s van, without her.

Chris and Roberta Laundrie have not been charged with a crime in connection with Petito’s death.

Petito and Schmidt are also suing the Moab Police Department over the domestic violence stop.