Among other possibilities, Utah Code § 76-5-107

(2) (a) An actor commits a threat of violence if the actor: (i) (A) threatens to commit an offense involving bodily injury, death, or substantial property damage; and (B) acts with intent to place an individual in fear of imminent serious bodily injury, substantial bodily injury, or death; or (ii) makes a threat, accompanied by a show of immediate force or violence, to do bodily injury to an individual. (b) A threat under this section may be express or implied.

They showed up with an arrest warrant. Unless and until there's some evidence where they just rolled up with the intent to murder him, I'm going to presume that's not the case.