Idaho Code (I.C.)
TITLE 19. CRIMINAL PROCEDURE
CHAPTER 6. ARREST, BY WHOM AND HOW MADE
19-604. WHEN PRIVATE PERSON MAY ARREST.
A private person may arrest another:
1. For a public offense committed or attempted in his presence.
2. When the person arrested has committed a felony, although not in his presence.
3. When a felony has been in fact committed, and he has reasonable cause for believing the person arrested to have committed it.