Kristin Cavallari's brother Michael believed to have died of exposure

Kristin Cavallari's Brother Michael May Have Died From 'Exposure to the Elements'
Kristin Cavallari's Brother Michael May Have Died From 'Exposure to the Elements'

The Grand County Sheriff's office tells ET that they believe exposure to the elements is the cause of death in the case of Michael Cavallari, brother to reality star Kristin Cavallari.

No drugs, alcohol, or weapons were found at the scene of Michael's death, which is not being investigated as a suicide, as no note was recovered. Michael's body was found three miles from his car. Investigators believe the cold weather in Grand County, Utah indicate that hypothermia may have been a factor in the 30-year-old's death.

Kristin, 28, confirmed the news of her brother's death to ET on Thursday, saying, "We want to thank everyone for their love, support and prayers during this very difficult time. We have just been informed by the authorities my brother's body has been found. This is a very painful time and we are still processing it all. We kindly ask everyone please respect our privacy during our time of grieving."

After releasing the statement, the former Laguna Beach star posted a moving message to her brother on Instagram, "My heart is in a million pieces. Mikey, I could always count on you to make me laugh. You had such a good heart and will be forever missed. I'm at a loss for words but I know u are in a better place and finally at peace. I love u so much RIP."

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

A photo posted by Kristin Cavallari (@kristincavallari) on Dec 10, 2015 at 1:42pm PST

After his death, a close friend of Michael's from college spoke out to ET, calling him a "good person with a good heart" who would "light up the room."

"Michael was very sweet. He was always very caring and loyal," the friend shared. "He was the one everyone turned to for laughs."

WATCH: Police: Kristin Cavallari's Brother Was Arrested With a Shotgun Prior to His Disappearance

"He was very close with Kristin," the friend added. "He took a huge interest in his family. He was really protective of Kristin. He was the stereotypical big brother, so protective of Kristin and just really cared about his family."

Prior to Michael's disappearance and death, he was arrested on Nov. 23 -- the same day as Kristin and her NFL player husband Jay Cutler welcomed their third child -- for making "criminal threats" after an unnamed female reported him to the police.

WATCH: Kristin Cavallari Shares Sweet Flashback Photo of Her Missing Brother, Thanks Fans for Prayers and Support

The informant told Sheriff's deputies that she heard a "tapping" on her door, and when she looked out the window, she saw Michael standing in the walkway between her apartment and the parking lot "with a shotgun pressed to his shoulder and the barrel raised parallel to the ground, aiming down the path." The statement from the Sheriff's Department adds, "While responding to the address, Michael Cavallari notified dispatch he had a shotgun and was going to Dana Point City Hall."

Michael -- who allegedly had "a strong odor of an alcoholic beverage coming from his breath" when arrested, according to the Sheriff's Department report -- denied "doing anything or saying anything to the victim/informant."

WATCH: Kristin Cavallari's Brother Michael Found Dead Days After Reported Missing

Michael was released from jail after making bail on Nov. 25, and his car was found abandoned two days later.

Watch the video below for Kristin's message to her brother.

Kristin Cavallari's Brother Was Arrested Before He Went Missing, She Speaks Out
Kristin Cavallari's Brother Was Arrested Before He Went Missing, She Speaks Out