Rumors were rife on QAnon Telegram channels, with commenters suspecting Petito of being part of a cover-up for the Biden administration.
Authorities are still searching for Laundrie, who has been missing since last Tuesday, and is a person of interest in Petito's homicide.
The couple went out to lunch at a restaurant in Jackson, Wyoming, on Aug. 27, when they said they saw Laundrie "aggressively" arguing with a waitress.
Gabby Petito posted about her life with fiancé Brian Laundrie, travel, and reading a book about the Zodiac killer.
The fact that Laundrie disappeared three days before his family reported him missing presents a huge challenge for police, the expert told Insider.
A photo of Gabby Petito - which has since been removed - was added to a Yelp page for Steven Bertolino. Negative reviews also flooded the page.
Florida police said on Wednesday that the "search continues" for Laundrie, who was reported missing by his family on Sept. 17.
"In the eyes of the public you are as guilty and complicit with this massive cover-up and stalling tactic," Gabby Petito's uncle, Steven, wrote online.
Footage from outside Brian Laundrie's home is going viral online amid massive public attention on the disappearance of 22-year-old Gabby Petito.
Police said Wednesday that the "search continues" for missing Brian Laundrie, whose parents said he did not return from a hike in the Carlton Reserve.
Gabby Petito seemed anxious that Brian Laundrie would leave her and take her phone, a witness said of their August 12 Utah row.
The murder of Gabby Petito highlighted disparities in media coverage for missing women of color. Experts call for legislation that would protect them.
Police in Alabama and Florida publicly shot down rumored sightings of Laundrie, Gabby Petito's boyfriend, but they're still drawing a blank.
"If she can show Utah some love, we can show her some love, and come together with one another in her memory," organizer Jack McMahon said.
Brian Laundrie is considered a "person of interest" and has not been charged with any crime in the disappearance of Gabby Petito.
Jessica Schultz, a camper who said she saw the white van belonging to Gabby Petito and Brian Laundrie, said she told the FBI to look at the campsite.
Steven Bertolino, an attorney working for Petito's fiancé and his parents, told Insider in response to the recent development in the case.