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

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.

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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.

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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. 

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.

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

U.S.Missing PersonsCrime and Public Safety