Gabby Petito: Search for missing woman continues; Brian Laundrie is person of interest: LIVE UPDATES

Lara Yeretsian, a criminal defense attorney based on the west coast, said that complicated cases like the disappearance of Gabby Petito need to be taken day-by-day, but she thinks an arrest could come soon.

"I wouldn't be surprised if there's an arrest, an arrest of the fiancé," Yeretsian said Thursday.

"Fiancés are going to want to help. Most fiancés who love their girlfriend or their significant other, they're going to do everything in their power to help. This tells me something is not right."

Protesters gathered outside the Brian Laundrie's home in North Port, Florida on Thursday evening to protest his silence on the disappearance of his fiancée, Gabby Petito.

Some carried signs and drove by in golf carts while others chanted, "Where's Gabby?"

Laundrie was named a person of interest in Petito's disappearance on Wednesday and has refused to cooperate with authorities on the advice of his attorney, according to police.

The sister of Brian Laundrie, who is not cooperating with authorities in the disappearance of his fiancée, broke the family's silence on Thursday.

"Obviously me and my family want Gabby to be found safe," Cassie Laundrie told ABC. "She's like a sister and my children love her, and all I want is for her to come home safe and found and this to be just a big misunderstanding."

Brian Laundrie has retained a lawyer and remained silent about the disappearance of Gabby Petito late last month, according to the North Port Police Department.

Petito's family has pleaded with Laundrie and the rest of his family to come forward with any information.

"We believe you know the location where Brian left Gabby. We beg you to tell us," a letter from the Petito family to the Laundries said.

"Gabby lived with you for over a year. She was going to be your daughter in law. How can you keep her location hidden? Please, if you or your family have any decency left, please tell us where Gabby is located. Tell us if we are even looking in the right place."

Brian Laundrie's lawyer said Thursday night that law enforcement "has to follow protocol and all leads that they get," but any potential connection between the disappearance of Gabby Petito and a double homicide in Moab last month will be determined at a later date.

"Law Enforcement has to follow protocol and all leads that they get," the attorney, Steven Bertolino, said in a statement Thursday night. "Whether or not these two cases deserve to be linked will be determined at some point in the future."

A family drove their golf cart by Brian Laundrie's family home in North Port, Florida on Thursday with signs urging him to speak up in the search for Gabby Petito.

The last time Gabby Petito's mother had a verbal conversation with her daughter was on Aug. 25, when she was in Grand Teton National Park with her fiancé, Brian Laundrie.

Petito's stepfather, Jim Schmidt, traveled to Wyoming this week to assist in the search and investigation.

"The police, law enforcement agencies are all working together out here. They’re all actively investigating any leads they have," Schmidt told Fox News Thursday. "Right now, we’re just here to support them and help them with anything they may need."

Gabby Petito's last known location was in Grand Teton National Park in late August.

She told her mom that she was going to Grand Teton, then eventually Yellowstone with her fiancé, Brian Laundrie.

The Grand County Sheriff’s Office said it is not ruling anything out and is looking into whether the disappearance of Gabby Petito could be connected to a double homicide that occurred at a campground near Moab last month. 

“The Grand County Sheriff’s Office has been in contact with Florida authorities and we are actively looking into any connection between the Gabby Petito missing person case and the double homicide that occurred in Grand County," the sheriff said in a statement Thursday.

"The Sheriff’s Office is not ruling anything out at this time and appreciate the concerns of the public and their willingness to contact this office with those concerns and information.”

Crystal Turner, 38, and Kylen Schulte, 24, were found shot to death at a campground outside Moab in mid-August, five days after they were last seen leaving a downtown Moab bar on Aug. 13. 

Schulte worked at the Moonflower co-op, which is the same store that Petito and her fiancé, Brian Laundrie, got into a physical altercation near on Aug. 12, according to a police report obtained by Fox News.

Emily Stock, the Board President of the Moonflower co-op, told Fox News that no one from the store witnessed the altercation on Aug. 12.

Gabby Petito's stepfather, Jim Schmidt, called out his stepdaughter's fiancé for not cooperating with authorities or assisting the investigation.

"You say she’s the love of your life. She’s missing. You were on a trip with her, but you have no comment. You have nothing to say and you’re hiding behind an attorney," he told Fox News on Thursday.

"I understand the constitutional rights that people have, but you have pieces to this puzzle that we need to find Gabby and you’re withholding them from us."

Gabby Petito's last known location was the Grand Teton National park in late August.

The 22-year-old grew up in Blue Point on Long Island but lived with her fiancé's family for roughly two years in Florida before embarking on a cross-country road trip this summer.

Gabby Petito's family put out a desperate plea for her fiancé, Brian Laundrie, and his family to help them find the missing woman.

"We believe you know the location where Brian left Gabby. We beg you to tell us," a letter read by the family's lawyer at a press conference Thursday said.

"Gabby lived with you for over a year. She was going to be your daughter in law. How can you keep her location hidden? Please, if you or your family have any decency left, please tell us where Gabby is located. Tell us if we are even looking in the right place."

Gabby Petito's friends and family are desperately seeking answers in the 22-year-old's disappearance.

"Gabby made a mark on anyone she came in contact with. Even it was a quick interaction," her best friend told Fox News. "She not only sees the light in everyone but spreads her light with everyone. At my lowest she managed to help me keep my chin up."

Gabby Petito was reported missing on Sept. 11, roughly two weeks after her family last heard from her.

Fox News has obtained the bodycam footage showing officers interacting with Gabby Petito and Brian Laundrie after a witness called 911 around two weeks before she disappeared to report a “possible domestic violence” incident.

Click here to read more.

Joe Petito tells reporters gathered at an ongoing press conference Thursday that "what I need from everybody here is help.

"The goal is still not met and that goal is to bring Gabby home safe. I’m asking for help from everyone here, I’m asking for help from everyone at home, I’m asking for help from the parents of Brian and I’m asking for help from the family members and friends of Laundrie family as well," he said.

"There is a tip line you can call anonymously. Whatever you can do to make sure my daughter comes home I’m asking for that help. There is nothing else that matters to me now," he added.

Authorities are asking anyone with information about the case to contact the FBI's tip line at 1-800-CALLFBI (225-5324).

Media have swarmed the North Port, Fla. police department awaiting a highly-anticipated update from FBI, police, and Gabby Petito's family on her disappearance,

Click here to watch on Fox News.

Click here to watch on Fox News.

Sean Leahy, whose son went to school with Brian Laundrie – the person of interest in Gabby Petito’s disappearance – tells Fox News’ Stephanie Pagones Thursday that Laundrie was “quiet” and “a good kid growing up.” 

“The one thing that troubles me is that he came home. He didn’t say nothing,” Leahy said regarding the case. “And he got a lawyer.” 

Leahy added that “I don’t want to think the worst of him” and “I’m hoping for the best for her.” 

Leahy’s son, also named Sean, went to high school with Brian and Gabby.  

“All of this stuff coming out, I'm like surprised because every time I ever hung out with Brian, had classes with Brian, he was a really nice kid, a really funny kid,” he told Fox News. 

“I only met Gabby probably one or two times, three times. She, every time I met her, she was really nice," he added. 

Grand Teton National Park in Wyoming has released a missing person poster for Gabby Petito.

North Port Police Chief Todd Garrison tells ‘Fox & Friends’ on Thursday that Brian Laundrie is being considered a person of interest in Gabby Petito’s disappearance because “there is only one other person that was with her.”