Kristin Cavallari's Brother Michael Found Dead, Police Say

"My heart is in a million pieces," she wrote of her brother Michael's death.

"At approximately 10:30 a.m. search crews located remains believed to be that of Michael Cavallari. At this time, the body is being transported to the Office of the Utah Medical Examiner for positive identification and to determine the cause of death," The Grand County Sherriff's Office in Utah said in a press release on Thursday.

The release added, "The terrain where the body was located is a steep and very rocky area."

Cavallari herself added in an Instagram post, "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."

Michael went missing shortly after Thanksgiving and his car was found abandoned by Utah authorities, according to the Grand County’s Sheriff’s Office.

"At this time, the Grand County Sheriff's Office is handling this matter as an active missing person investigation," authorities wrote on the office's official website on Dec. 5.

"I appreciate all the concern, thoughts, and prayers that have been extended to me and my family," she wrote on the social media site. "We remain hopeful and I will share any news that we receive. I have such gratitude for all those that have shared their support."

A request for comment from Cavallari's rep was not immediately returned to ABC News.