He can pat down in the course of an investigation if he has "reasonable suspicion" that the person could be armed.
Pat-Down Searches
Pat-Down Search
A pat-down search is when a police officer pats down the outer surfaces of a person’s clothing in an attempt to find weapons. A pat-down searchconstitutes a search under the Fourth Amendment. Pat-down searches, incident to an investigatory stops, are usually made without a warrant and justified if the officer has reasonable suspicion that the person being searched is armed and dangerous. The reasonableness of suspicion is reviewed based on the totality of circumstances and both the subjective individual experience of the officer and the objective factors at the time would be taken into consideration. For instance, in Rogue v. States, 311 Ga. App. 421, 715 S.E. 2d 814 (2011), the court found that because the police lacked specific information about the vehicle passenger during a valid traffic stop, the police officer did not have reasonable suspicion that the passenger was armed and dangerous; therefore the police officer was not justified in the pat-down search of the passenger.
Pat-down
searches serve to ensure the officer’s safety, and thus, the conduct should not exceed what is necessary to serve that purpose. Objects obtained during a pat-down
searchshould be immediately identifiable to be admissible evidence. If, during a pat-down, the officer feels an object he
reasonably suspects may be a weapon by its contour, the officer may reach for the object and remove it. The officer may also
seize the objects during an otherwise legitimate pat-down
search if by
plain feel he
reasonably believes it to be
contraband.
You know what gives reasonable suspicion?
Not cooperating. That is almost universally going to be considered suspicious behavior by a court.