Brian Laundrie's sister says she hasn't spoken to her parents in two years amid fallout from a new docuseries that reveals text messages between her and her mom that shows them joking about how police let Gabby Petito's killer slip out under their nose before ultimately killing himself in a park nearby.

"If you’re new here. And just starting to attack me today. I’ve been non contact with my parents for almost two years," Cassie Laundrie wrote on Instagram. "Have fun."

Brian Laundrie's older sister is disputing statements from a police detective overheard in bodycam video from the night police first knocked on her door as they began the search for missing Petito on Sept. 11, 2021.

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Suffolk County Police Detective Tracey Barry initiated the missing person case from New York after authorities in other jurisdictions declined to take action despite desperate pleas from Petito's mom, Nichole Schmidt.

Barry can be heard telling a North Port police officer over the phone that Cassie Laundrie told her about a fight between the couple.

Cassie Laundrie said no one from either family, hers or Petito's, contacted her until after Barry reached out.

"Det. Barry gravely miscommunicated what I told her in the phone," Cassie Laundrie wrote.

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In police bodycam first obtained by Fox News Digital in September and re-aired in the new Netflix docuseries, "American Murder: Gabby Petito," Barry tells a North Port police officer over the phone that the presence of Petito's van in the Laundrie parents' driveway after her disappearance appears suspicious.

"His sister told me another story that he left her out there and flew home, and yet you're seeing the van in their driveway, and they won't say where she is," Barry says. She notes that the vehicle is registered to Petito and says her family considers it hers.

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"I had called his sister. She called me back and said, ‘Oh, Brian’s home. He told me they got into a fight. He left her at a hotel, and he flew back,'" Barry says in the call. "I dunno what's going on, but it's pretty shady."

About two weeks before Petito's murder, the couple was involved in a domestic violence dispute in Moab, Utah, during a cross-country road trip that Petito hoped would launch her career as a budding social media influencer and travel blogger. Police split them up for the night, but they later reunited.

Laundrie then flew home to Florida for almost a week, leaving Petito at a hotel in Salt Lake City. He flew back, and they resumed their trip.

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Cassie Laundrie did not immediately respond to a request for comment.

She has also claimed on social media that she witnessed her brother being a victim of domestic violence at the hands of Petito.

Petito's family has rejected that version of events.

"Cassie Laundrie is spewing lies, evidence and actions speak louder than words," Schmidt told Fox News Digital.

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According to an FBI timeline, Brian Laundrie is believed to have killed Petito alongside Spread Creek in the Bridger-Teton National Forest in Wyoming on Aug. 27, 2021. 

According to the FBI, he staged the scene, made fake communications between his phone and her phone, transferred himself hundreds of dollars from her bank account and drove home to Florida in her van. After he arrived, he went camping for Labor Day with his parents as well as Cassie's family in Fort De Soto Park, south of St. Petersburg.

The siblings saw each other on both Sept. 1, the day Brian Laundrie returned home from Wyoming, and Sept. 6, when Cassie Laundrie, her husband and children spent six hours at the Fort De Soto campsite.

When police knocked on his door looking for Petito on Sept. 11, he refused to cooperate. He snuck out on Sept. 13, but the Laundries did not tell police until days later.

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By then, he was dead, but his remains went undiscovered for more than a month.

Text messages revealed in "American Murder: Gabby Petitio" show Cassie and Roberta Laundrie joking about how police let the suspect, who was under surveillance, slip out under their noses.

"The north port police said Brian and I have a ‘similar build’ boy, Brian would not be happy about THAT!!" Roberta Laundrie texted to her daughter.

"Yea everyones laughing at that remark because not even remotely close," Cassie Laundrie replied.

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"short, pudgy and big bottomed!" Roberta Laundrie wrote back. "Or short sassy and shapely! (Pear shaped!)"

"Lol must have just been that hat!" Cassie quipped. "Put their top notch guys on surveillance."

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Cassie Laundrie has long denied knowledge of what happened between her parents and brother during the search for Petito. 

"We are just as upset, frustrated and heartbroken as everybody else," she said outside her home in October 2021. "I am losing my parents and my brother and my children’s aunt and future sister-in-law on top of this."

The sister was supposed to be deposed in a lawsuit in which her parents were sued by Petito's parents – but her interview was canceled. The sides reached an out-of-court settlement last year.

If you or someone you know is suffering from domestic violence, please contact the National Domestic Violence Hotline at 1−800−799−7233 (SAFE).