What is the test for probable cause in a case of mistaken identity?

¹ A case of mistaken identity is not an exception to the probable cause requirement. "Probable cause to arrest exists when officers have knowledge or reasonably trustworthy information sufficient to lead a person of reasonable caution to believe that an offense has been or is being committed by the person being arrested." United States v. Lopez, 482 F.3d 1067, 1072 (9th Cir. 2007) (emphasis added) (citing Beck v. Ohio, 379 U.S. 89, 91, 85 S.Ct. 223, 13 L.Ed.2d 142 (1964) ). Thus, an arrest warrant coupled with a reasonable belief that the person being arrested is the subject of the arrest warrant gives rise to probable cause to arrest that person. On the other hand, an arrest based on an unreasonable belief that the person being arrested is the subject of the arrest warrant offends the Fourth Amendment.