[BeHoldAPaleHorse]

Tell the person, "You are under citizens arrest"

Now, you need to take the person to or call the cops to take custody from you. A state trooper will do.

Cop tells you, "You are charged with the offense of false arrest."

Cellmate tells you: "Hi, honey, my name's Spike."

[BorderRaven]

The charge of "false arrest" is a scare tactic, to make you rethink your actions, so they can avoid their job, but if your are making a lawful arrest, then false arrest won't stick.