Michael Cavallari's Death Ruled an Accident, Autopsy Report Says He Died of Hypothermia

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A medical examiner has determined the cause of death of Kristin Cavallari's 30-year-old brother,  Michael Cavallari.

The death of Jay Cutler's brother-in-law was ruled accidental after his car crashed while passing through a mountainous, rural part of southern Utah, ET has learned. The medical examiner's report says Michael died of  hypothermia due to the below-freezing temperatures.

WATCH: Kristin Cavallari's Brother Michael Found Dead -- A Timeline

According to Grand County Sheriff Steven White, officials are still waiting on the toxicology report to determine if any drugs were in Michael's system at the time of his death.

Michael's body was found nearly two weeks after his abandoned car was located by a rancher about 200 miles south of Salt Lake City, Utah. Police say the engine was still running and the air bag was deployed when they the vehicle was located. Michael's body was found on Dec. 10 at the bottom of a steep hill.

MORE: Kristin Cavallari Has a New 'Appreciation for Life' After Car Accident and Brother’s Death

Four days prior to when his car was found, Michael was arrested in California on allegations that he threatened a woman while armed with a shotgun.

Just over a month after the death of her brother, Kristin was involved in a car accident  herself that sent her to the hospital and left her with minor injuries. "I'll be honest, getting in this car accident and everything else that's been going on in my life the last few months. I have such an appreciation for life," The Hills star told ET's Jennifer Peros  earlier this month.  "I'm just grateful for everyone and everything in my life."