TMZ has obtained the search warrant cops got days after Heather was arrested for felony domestic violence. We were told cops were looking for a gun, but it turns out they were on the hunt for other items, including Rx pills.

According to a Ventura County Sheriff's deputy, when cops arrived the boyfriend, Christopher Heisser, was standing on the side of the bed leaning over Heather and holding her wrists while she was on the bed.

Cops said they observed Heisser bleeding from the bridge of his nose and redness on his chest. He told deputies Heather attacked and repeatedly struck him -- and he defended himself. He said she bit his face as she acted "crazy, angry and wild."

She told cops the fight started after he lied to her -- she did not elaborate on the lie -- and she threw a can of Red Bull at him. She told cops Heisser choked her to the point she couldn't breathe, but also claimed she had no marks on her neck.

She then became belligerent with the cops, telling them, "Get out of my f****** house," charged at them, grabbed one on the arm and later kicked him in the shin.

Cops say they eventually grabbed her and cuffed her on the ground. But, officers say she was still so belligerent, they had to put a hobble on her to prevent her from kicking them.

Cops got her outside, pinned her against her car and she screamed, "You f****** deserve your kids to die! You f****** deserve it! And when you find yourself in that position, think of me!"

She went on ... "I hope no one f****** burns your entire department down, your f******* police department ..." She then said what triggered the search warrant ... "Get the f*** off my property. Don't ever come on it. All of you are not allowed ... I will shoot you if you come on my property and take that as a threat and f****** put another count against me."

Heather's daughter, Ava, was present when cops were there and said Heather had been drinking. Heisser was arrested hours afterward for DUI.

During the investigation cops discovered she had a .38 Smith & Wesson revolver registered in her name.

When they went to her home with the search warrant, they were looking for the gun, but also ammunition, holsters, paraphernalia related to firearms, prescription bottles, diaries, clothing, mail and various other items.

The search warrant notes Heather had a history of drug and other alcohol-related incidents, including a call in 2012 where she was reported to be suicidal.

Cops did not find a weapon.