Possible law enforcement agents at home of Brian Laundrie's sister in Lakewood Ranch

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Possible agents at home of Cassie Laundrie

Courtesy Fox News

Two people believed to be law enforcement officers were seen entering the home of Cassie Laundrie, the sister of Brian Laundrie, a person of interest in the disappearance of Gabby Petito, Monday afternoon. 

Fox News was outside of the home Monday when the pair showed up. They spoke to a person believed to be Cassie Laundrie outside of the home before being allowed to come in. 

Cassie Laundrie lives in Lakewood Ranch, about 35 miles north of her parents' home in North Port.

MORE: FBI concludes search of Laundrie family home in connection with Gabby Petito's disappearance

As the two men entered Cassie’s home, the FBI was in the process of executing a warrant at her parents' home.

All of the activity is centered around the search for Brian Laundrie, the fiancé of Gabby Petito, who went missing while the pair was on a cross-country trip in her camper van. 

Gabby Petito case: Timeline of 22-year-old woman's disappearance

Brian and the van ended up back at Brian’s parents’ home in North Port on September 1, but Gabby was nowhere to be found. 

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How the new 911 calls fit into the timeline

We're now hearing details of the 911 call that prompted a police stop before Gabby Petito -- and, later, Brian Laundrie -- disappeared.

RELATED: Gabby Petito investigation: 911 call reveals Brian Laundrie seen hitting, 'slapping' her before disappearance

A search of the Grand Teton National Park, where Gabby told her mother on August 25 the couple was visiting after they left Utah, turned up human remains believed to be those of Gabby.

Brian and Gabby had been living at Brian’s parents’ home in North Port before they left for their trip.

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Full interview: Woman who spotted Gabby Petito's likely van

On August 27, the Bethune family was trying to find a spot to camp for the night when they found themselves in the Spread Creek camping area near Grand Teton National Park, where remains were found Sunday matching Gabby's description. Jenn Bethune said the van they passed by appears to be the converted camper van that Petito and her fiancé – and person of interest --Brian Laundrie, were using to travel.

MORE: Gabby Petito’s possible remains found near where Tampa family spotted camper van