Designer and former reality TV star Kristin Cavallari thanked fans Monday as she and her husband, Chicago Bears quarterback Jay Cutler, awaited word on the fate of her brother, Michael, who has gone missing in Utah.

“I appreciate all the concern, thoughts, and prayers that have been extended to me and my family,” Cavallari, 28, formerly of MTV reality shows “The Hills” and “Laguna Beach,” posted on Instagram alongside an image of herself and her brother as children. “I have such gratitude for those that have shared their support.”

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Sheriff Steven White of Grand County, Utah, told Salt Lake City TV station KSL his office received a call on Nov. 27 by someone reporting what turned out to be an abandoned 2014 Honda Civic in the desert about 100 feet from a road, five miles off Interstate 70’s Exit 175. The remote location is 225 miles southeast of Salt Lake City, between Green River and Crescent Junction.

StoryKristin Cavallari’s missing brother found dead

The car, which appeared to have hit a large rock, was found with its engine running and its air bag deployed. “We’re combing the area for anything we can find,” White told the station. “We’re deeming it suspicious, but there’s nothing to indicate anything one way or another. The vehicle was just abandoned.”

After finding a laptop and cellphone, the sheriff’s office used the vehicle’s registration to trace it to Michael Cavallari, 30, of San Clemente, California. Video surveillance from a convenience store in Monticello, Utah, in adjacent San Juan County to the south, showed Cavallari was the person making the last known use of his credit card.

The organization Missing Persons of America posted a notice saying Michael James Cavallari is “roughly 5’11”, thin, brown hair, beard” and that, “We believe he was trying to get to Illinois.”