VENICE, Fla. (WFLA) — Brian Laundrie’s mother wrote a letter to her son that included an offer of baking a cake with a shiv inside to help Brian if he were sent to prison for Gabby Petito’s murder, according to a new court filing by the attorney for Gabby Petito’s parents.

In the court filing in Sarasota County Circuit Court, Pat Reilly, who is representing Joe Petito and Nichole Schmidt in a lawsuit against the Laundries, is arguing for the release of the “burn after reading” letter written by Roberta Laundrie to her son Brian to prove she was allegedly aware of Petito’s murder in August 2021.

“The letter in question, written by Roberta Laundrie to Brian Laundrie references bringing a shovel to help bury a body, and baking a cake with a shiv in it should Brian Laundrie go to prison. A reasonable inference is that the letter was written at a time when Gabrielle Petito was as yet unburied, and Brian Laundrie could go to jail for the crime of murder.”

Reilly says the letter was collected by the FBI as evidence and released back to the Laundries earlier this year. He says he has seen the letter, which is said to have “burn after reading” written on the envelope.

In previous interviews with the media, Reilly has alluded to Roberta Laundrie allegedly offering to bake a cake with a “knife” or a “saw” inside to assist in Brian’s escape from prison, however, this is the first time the claim is referenced in a court filing.

In March, Roberta Laundrie wrote a motion to the court and confirmed the letter’s existence but insisted it had nothing to do with Gabby Petito. She claims it was written months before Gabby and Brian left on their cross-country road trip in the summer of 2021.

“The purpose of the letter was to reach out to Brian while he and I were experiencing a difficult period in our relationship,” Roberta wrote in the court motion to protect the letter from release. “Brian and I always had a very open and communicative relationship and in the months prior to the trip our relationship had become strained. Brian and I shared a love of stories and some of the language in the letter was using similar phrases to describe the depth of a mother’s love.”

Petito and Schmidt are suing the Laundries and their longtime attorney Steven Bertolino for intentional infliction of emotional distress. They claim the Laundries and Bertolino were aware of Gabby’s murder in August 2021 but refused to do anything other than release a statement expressing hope Petito would be found.

Reilly, in the court filing, says he believes a jury should decide when the letter was written and if it has any connection to Petito’s death.

“If the jury were to find that the letter was written after Gabrielle Petito’s murder, it is further proof that the Laundries and Bertolino were aware that she was deceased at the time the statements in question were issued. If it was not written at a time when Roberta Laundrie knew that her son had murdered Gabrielle Petito, it is at best an odd letter for a mother to write a son, and Roberta Laundrie’s explanation for writing it is frankly unbelievable.”

In March, Roberta admitted that her letter does contain references that some would think are about her son and Petito, however, she claims there is “no connection” between her words and what happened to the couple.

“While I used words that seem to have a connection with Brian’s actions and his taking of Gabby’s life, I never would have fathomed the events that unfolded months later between Brian and Gabby would reflect the words in my letter. The words in the letter could never have been a comment on that tragic situation as they were written so many months before. My words to Brian were meant to convey my love and support for my son through a light-hearted and quirky reminder that my love for him was not diminished and could not be shaken by the miles of separation we would soon be faced with.”

Judge Danielle Brewer has scheduled a hearing on May 24 to rule on whether the “burn after reading” letter should be granted to Petito and Schmidt in the discovery process and included in the trial, which is slated for May 2024. Brewer will also rule on Bertolno’s motion to dismiss, which Reilly contends should be denied in part due to the Laundrie’s previous dismissal attempt being rejected.