01:09 - Source: KSL
Kristin Cavallari's brother missing in Utah

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Michael Cavallari's abandoned car was found last month

Authorities said the case is an active missing person investigation

CNN  — 

Utah authorities are looking for the brother of reality TV star Kristin Cavallari after his car was found abandoned.

Grand County dispatch got a call about an unoccupied Honda Civic on November 27, authorities said.

When authorities got to the scene along Interstate 70, there was no sign of Michael Cavallari.

Investigators determined he was driving the car registered to him. A search of the surrounding areas turned up empty, according to the Grand County Sheriff’s Office.

Authorities said the case is an active missing person investigation.

“Credit card transaction receipts also led investigators to a convenience store in Monticello, Utah,” the Grand County Sheriff’s Office said.

“Upon reviewing the security footage from the convenience store, the driver of the vehicle was positively identified as Michael Cavallari.”

Kristin Cavallari is married to Chicago Bears quarterback Jay Cutler. She rose to fame as a cast member of reality shows “Laguna Beach” and its spinoff series, “The Hills, which detailed her life and that of her friends in Southern California.

Michael Cavallari lives in San Clemente, California, authorities said.

CNN’s Joe Sutton contributed to this report