Kristin Cavallari has released a statement about her brother Michael Cavallari's disappearance as more details from the investigation emerge, including an arrest on his record just days before going missing.

"I appreciate all the concern, thoughts, and prayers that have been extended to me and my family. We remain hopeful and I will share any news that we receive. I have such gratitude for all those that have shared their support," Kristin captioned a photo of the two siblings together when they were younger on Instagram yesterday.

Kristin was "always very protective" of her brother growing up, said a People source.

Authorities have been searching for Michael, 30, via foot and helicopter after his 2014 Honda Civic was found abandoned on a remote dirt road in Utah with its engine on and the airbag deployed one day after Thanksgiving. No traces have been found.

According to Fox News, Michael was on a road trip by himself to an undisclosed destination and likely hit a couple of big rocks. There were no signs of foul play, but temperatures in the area have dropped to below freezing in recent days.

Court documents show Michael had been arrested outside a city hall in southern California with a loaded shotgun just four days before his car was found on November 27 about five miles from I-70. A woman called police after she fought with an armed Michael outside of her apartment and feared for her safety.

As previously reported, Michael's latest credit card transactions and surveillance-camera footage prove he stopped at a convenience store in Monticello to ask for directions to Salt Lake City hours before his car was found. He reportedly made the stop at around 3:30AM.

Michael, who resides in San Clemente, CA, is also the brother-in-law of Jay Cutler, who plays for the NFL's Chicago Bears.

Kristin and Jay wed in 2013 and just recently welcomed a new baby, Saylor James, on November 23. Kristin appeared on MTV's The Hills and Laguna Beach. She later competed on the thirteenth season of ABC's Dancing with the Stars.