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

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While Kristin Cavallari's older brother, Michael Cavallari, remains missing, the Orange County Sheriff’s Department has just released shocking new information surrounding Michael's arrest last month.

According to an incident report obtained by ET, Michael, 30, was arrested on Nov. 23 after an unnamed female informant called the Sheriff’s Department to report Michael, with whom she says she had a “verbal dispute” on Nov. 11. The report says the informant told deputies that, “she was in fear of him” following the incident, “but did not contact the Sheriff’s Department because she didn’t want to escalate the situation.”

The Sheriff’s Department tells ET the informant reported that “for several weeks after the incident, Michael kept knocking on her door, but she refused to answer.” On Nov. 23, the informant said 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.”

WATCH: Kristin Cavallari's Brother Reported Missing

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.” According to the report, deputies responded to City Hall and contacted Michael, who had “a strong odor of an alcoholic beverage coming from his breath.”

Michael, who pleaded guilty to a DUI charge in Nov. 2014, then admitted to having a loaded shotgun in his trunk and was handcuffed and read his Miranda Rights, to which he stated “yes,” according to the Sheriff’s Department statement. The report adds that Michael “denied doing anything or saying anything to the victim/informant.”

Michael was released from jail on Nov. 25 after making bail, according to police records. He has now been missing for over 10 days. According to an officer from the Grand County Sheriff's Office in Moab, Utah, Michael was last seen on security cameras at a convenience store in Monticello, Utah. A 2014 Honda Civic registered in his name was found abandoned about 100 miles north of the shop in Grand County on Nov. 27, two days after he was released from jail.

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"Kristin is very distraught about her brother missing and is focused on working with authorities to find her brother," a source close to the Cavallari family told ET on Sunday.

"Michael has always been the troubled brother ... known for causing drama in the family," the source added.

Kristin, 28, thanked her fans on Twitter on Monday for their words of support.

"I appreciate the thoughts & prayers that have been extended to me & my family," she wrote. "I have such gratitude for those that have shared their support."

WATCH: Kristin Cavallari's Brother Michael Arrested Days Before He Went Missing