New surveillance video showing Gabby Petito and Brian Laundrie at a Wyoming Whole Foods store hours before her murder in the Bridger-Teton National Forest last year shows her appearing "small," "exhausted" and "scared," according to a body language expert who reviewed the footage.

Meanwhile, Laundrie looked "cavalier" and "nonchalant," Susan Constantine, the body language expert and president of the Human Behavior Academy, told Fox News Digital.

When the couple arrives at the store in Jackson on Aug. 27, 2021, Laundrie leads them through the parking lot with an air of arrogance, Constantine said.

"She felt very small," the expert said. "You could see it in her whole body language: her shoulders are always more scrunched over, she’s holding herself, her stride and everything."

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Petito walks slightly behind Laundrie through the parking lot, arms crossed, eyes down, guarded and unsure, she said. Laundrie had slammed the van door and sauntered ahead of her, hands in his pockets, except for right before entering the store when he appears to rub his nose.

"Any time they rub their nose it’s just agitation," Constantine said, which comes from irritation in the capillaries around the nostrils and cheeks. "So, when you’re irritated and frustrated, you sometimes scratch your nose."

But Laundrie's demeanor changed once inside the store, she said.

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Gabby Petito and Brian Laundrie shopping together

Gabby Petito and Brian Laundrie browsing the dairy aisle. (Jackson PD)

"When they were walking around in the store, it seemed very casual to me," the expert said. "I didn’t see anything in there that would’ve led me to believe that this would have led up to him murdering her. I didn’t see that."

Yet inside, Laundrie never took Petito’s hand, she noted. The couple rarely even looked at each other.

"If I were to see her in the store, I would go, ‘She doesn’t seem happy to me,’" Constantine continued. But, she added, Laundrie didn’t seem particularly aggressive: he never tried to grab or hold her or make any alarming gestures.

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"Abusers don’t abuse in front of other people," Constantine said. "They abuse when they’re in their own space, and they’re protected, where other people cannot see — like in the car outside."

Brian and Gabby walking into Whole Foods

Gabby Petito and Brian Laundrie arrive at the Whole Foods store in Jackson, Wyoming, on Aug. 27, 2021. (Jackson PD)

Still, the couple seemed cold and distant, she said.

"It doesn’t look like a close relationship there, a loving relationship," she said. "There’s space between them. There’s no connectiveness."

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As for Petito, she appeared diminutive and kept looking down, she said, which indicates she was feeling guarded, introverted and emotionally contemplative.

"She wasn’t really happy about being with him. I don’t know what happened in the conversation in the car, but apparently something was going on where she was upset," Constantine explained.

Brian Laundrie and Gabby Petito exit the store

Brian Laundrie and Gabby Petito leave the Jackson, Wyoming, Whole Foods store on Aug. 27. 2021. (Jackson PD)

They had just come from the Merry Piglets restaurant where Laundrie got into a public argument with waitstaff, witnesses told Fox News Digital last year. And there may have had lingering issues with their relationship. Two weeks earlier, they were involved in a domestic violence call in Moab, Utah. In the aftermath, Laundrie flew home for a week, leaving Petito in a hotel in Salt Lake City.

"Gabby yawns at one point, so she obviously was tired," Constantine said. "But overall, she’s always holding on to either her bag, or she’s got her hands out in front of her kind of hugging herself — that is a person who is not feeling really confident."

However, she said, there’s not enough from the video inside the store to indicate that she perceived a threat.

"If she were feeling threatened, she would not have been staying as close to him as she was," she said. "I see her more as a victim of a person who is more empowered or more powerful than her."

Gabby Petito's Ford Transit van leaving parking lot

Gabby Petito's van seen leaving the Jackson, Wyoming, Whole Foods on Aug. 27, 2021. (Jackson PD)

Laundrie took the lead through most of the video, she said, and when he touched Petito’s shoulder, that could indicate him trying to console her after the restaurant antics or another disagreement — a "push-pull" move common in abusive relationships.

"We already know the other pieces of the puzzle," Constantine said. "It makes more sense, what was transpiring emotionally in this relationship."

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After the couple left the store, they spent 20 minutes in their parking space.

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"They’re obviously having a discussion," Constantine said, although the couple’s body language is not visible during this time. "We know that he's berated her in the past, and it could've been him doing the same thing. He gets her into these closed environments, and then he starts to berate her."

Gabby Petito on a swing and wearing a knitted hat

Gabby Petito, 22, vanished while on a cross-country trip in a converted camper van with her boyfriend. (FBI Denver via AP)

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One other point that stood out, she said, is when Laundrie steps away from Petito "and he just kind of looks down that one aisle." 

"He’s standing there like he’s trying to figure out if there’s something out there," Constantine said. "But I also wonder, why was he looking down there?"

Petito’s mother, Nichole Schmidt, reported her missing on Sept. 11, 2021, but her parents now believe she was killed on Aug. 27, the same day the Whole Foods video was recorded.

Brian Laundrie talks to cops

Brian Laundrie as seen in bodycam footage released by the Moab Police Department in Utah. (Moab PD)

An FBI-led search effort uncovered Petito’s remains at a campsite north of Jackson on Sept. 19 – eight days after Laundrie returned to his parents’ house in Florida without her.

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He vanished on Sept. 13 and was found dead more than a month later of what the FBI described as a self-inflicted gunshot wound. Nearby, in a dry bag, was a note in which he confessed to killing Petito.

"We know the timeline, when she ended up being murdered," Constantine said. "So, we know that there was something percolating. That is evidence this relationship was not a close relationship."