See my post #102. As I read Utah Code, the officer is required to inform the detainee of his imminent arrest.
It’s be interesting to see the case law construing that section. The way I read it, it says the announcement must be made in the course of arresting him, not PRIOR to arresting him. It also has several exceptions, including one that could be argued to apply here.
Your post 102 is similar to other States codes for custodial arrest. The way it is implemented by departments may vary, but it allows for issuing preparatory commands for officer safety, such as, “Turn around and put your hands behind your back.” then applying the cuffs, and saying “You’re under arrest for _______.”