A rancher found Michael Cavallari's car early on Nov. 27, the day after Thanksgiving, Grand County Sheriff Steven White said Monday. It was about 200 miles south of Salt Lake City and 5 miles south of Interstate 70, in a part of the state home to several national parks.
"Not much new," White told FOX411. "We have ground teams back out working this area again today with some dog teams and some drones. Everyone else is conducting follow-up."
It's unknown why he was driving on a dirt road miles from the main highway. But evidence shows Michael Cavallari's 2014 Honda Civic hit a couple of big rocks and washes, likely causing the air bag to deploy, White said.
Temperatures in the area have been at or below freezing every night since the car was found in a wide-open area, up against a small embankment.
White says crews have been searching the area on foot and by helicopter but have found no trace of Michael Cavallari. But it's difficult to find footprints in the frozen ground, he added.
"Right now I don’t have any kind of an end time until we feel comfortable on the ground searches that he is not out here or until we run out of leads. We can’t go any further the other way."
There are no signs of foul play.
Hours before his car was found, Michael Cavallari -- who lives in San Clemente, California -- stopped at a convenience store about 60 miles away and asked for directions to Salt Lake City.
Credit card transactions and surveillance video show that at 3:30 a.m. Nov. 27, he was at a store in the town of Monticello.
Michael Cavallari hasn't made contact with anybody since his car was found, White said.
The sheriff said he may have been dealing with a few minor issues in his life but nothing major. He declined to elaborate.
Michael Cavallari works for his father's corporation, White said. He is single and has no kids.
Kristin Cavallari rose to fame in the mid-2000s when she appeared in the MTV reality series "Laguna Beach" and "The Hills." She and Cutler have three children together.
Cutler starred collegiately at Vanderbilt and now plays for the Chicago Bears in the NFL. The 32-year-old said little Sunday when asked about whether the situation with his missing brother-in-law was a factor in his team's loss.
"No," Cutler said. "We stayed focused, and we adjust better than anybody."
Cutler's head coach, John Fox, said Monday he's aware of the situation but doesn't know much about it. Fox said the franchise provides resources for players to deal with off-field issues, including sports psychologists.
The Cavallari family asked authorities to respect their privacy in the first days after Michael Cavallari disappeared. They decided allow police to go public this weekend in hopes that somebody might come forward with more information, White said.
Michael Cavallari's father and stepfather have been in Utah to help with the search, the sheriff said.
Police are gearing up to launch new searches but are first strategizing the best areas to look. People recreate at sand dunes in the area, and White said he's hopeful someone who was there knows something.
FOX411's Blanche Johnson and The Associated Press contributed to this report.