Michael's body was found three miles from his abandoned car in Utah on Dec. 10

By Lindsay Kimble and Dan Wakeford
Updated February 10, 2016 11:20 AM
Credit: Courtesy Grand County, Utah, Sheriff's Office

Michael Cavallari‘s cause of death has been ruled as hypothermia, the Grand County Sheriff’s Office said in a statement Tuesday.

The news comes nearly two months after the 30-year-old brother of reality star Kristin Cavallari was found dead in Utah, three miles from his abandoned car, on Dec. 10 after an extensive search in the desert outside of Green River.

“The Medical Examiner’s Office has determined the death as accidental with the cause of death, hypothermia from exposure to cold environmental temperatures,” the sheriff’s office said.

PEOPLE couldn’t immediately reach the sheriff’s office for further comment.

“This is what Kristin thought had happened, as she knew in her heart that he wouldn’t commit suicide, but there’s a sense of relief that this has been confirmed,” a friend of the star tells PEOPLE.

Details surrounding Michael’s death after he went missing for just under two weeks are still mostly unknown.

Investigators said in December that they suspect he crashed into a rock and eventually succumbed to the cold weather while trying to find help.

Grand County Sheriff Steve White told PEOPLE at the time that it was obvious Michael was “disoriented.”

Michel struggled with alcoholism, according to his family, but had been working toward sobriety. Toxicology results have yet to be released.

Just before embarking on his final drive, Michael had posted bail after being arrested in Orange County on Nov. 23 for violating his parole from a 2014 DUI.

“It’s unclear what his state of mind was during this time, and that has them puzzled,” a family source previously told PEOPLE of the Cavallaris. “He had his ups and downs, but was turning his life around.”