Kristin Cavallari's brother missing in Utah

A missing person's search is underway in Utah to locate the whereabouts reality TV star Kristin Cavallari's older brother.

Michael Cavallari's 2014 Honda Civic was found abandoned in Grand County on 27 November (15), the day after the Thanksgiving holiday.

The California resident's car, which was discovered with its engine running and its airbag deployed, appeared to have hit a large rock on the side of Interstate 70, according to Grand County Sheriff Steven White.

Authorities were able to identify the driver from convenience store receipts found in the vehicle, along with Michael's laptop and cell phone.

Police officials are now appealing to members of the public for information to help track down the 30 year old.

"We're combing the area for anything we can find," White tells deseretnews.com. "We're deeming it suspicious, but there's nothing to indicate anything one way or another. The vehicle was just abandoned."

Cops reveal Michael, who is described as five foot, eleven inches (1.8 meters) tall, slim build with brown hair and a beard, was last seen wearing a green sweatshirt, jeans and black shoes.

Kristin, who is married to Chicago Bears quarterback Jay Cutler, has yet to comment on the her brother's disappearance.

The news emerges less than two weeks after the former The Hills star, 28, welcomed her third child with Cutler, a daughter named Saylor.

The couple, which wed in 2013, is also parents to sons Camden Jack, three, and Jaxon Wyatt, one.