In Arizona v. Hicks (1987) 480 U.S. 321, the police had entered an apartment after a gunshot had been fired into it. Their warrantless entry into the apartment to investigate and to aid any injured occupants was held to have been justified; and their discovery of guns, masks, and expensive stereo equipment, in plain sight once they were inside, was held to provide them probable cause to believe the stereo equipment was stolen. But no exigency justified the officers in then examining the equipment without a warrant in order to verify from a serial number on the bottom that it was stolen. The serial number was not in plain sight to the officers from a place where they were justified in being. The officers' examination of the serial numbers on the bottom of the equipment was unrelated to the objectives that had authorized their intrusion into the defendant's apartment--the determination whether any occupant of the apartment needed aid. Examining the bottom of the equipment constituted "a new invasion of respondent's privacy unjustified by the exigent circumstance that validated the entry"--a warrantless search--because it exposed otherwise-concealed portions of the premises and its contents. (Id. at p. 325.) The officers lawfully entered the defendant's apartment in search of weapons after shots were fired from the apartment. (Id. at p. 323.) One of the officers noticed expensive stereo equipment that appeared to be out of place in the squalid apartment. (Ibid.) Suspecting that the items had been stolen, the officer read and recorded the serial numbers. (Ibid.) However, in order to do so, he moved some of the equipment. (Ibid.) This movement, the Supreme Court held, constituted a search for which probable cause was required (id. at pp. 324, 326); the prosecution conceded that the officer did not have probable cause to believe the equipment was stolen until he moved it (id. at p. 326); and therefore, the court held further, the movement of the equipment constituted an illegal search (id. at pp. 326-327).The Supreme Court held that the officers did not have legal justification to move the equipment, and therefore the serial numbers thus brought into view could not lead to admissible evidence. Id. at 325. Upholding an order suppressing the seizure, the Supreme Court ruled as follows: But taking action, unrelated to the objectives of the authorized intrusion, which exposed to view concealed . . . contents, did produce a new invasion of respondent's privacy unjustified by the exigent circumstance that validated the entry. This is why . . . the "distinction between 'looking' at a suspicious object in plain view and 'moving' it even a few inches" is much more than trivial for purposes of the Fourth Amendment. . . . A search is a search, even if it happens to disclose nothing but the bottom of a turntable. Id. at 325. Significantly, the Court ruled that a police officer must have probable cause, not merely reasonable suspicion, to believe that the discovery of an item during a search, which was not the focus of the search, is evidence of a crime or is contraband. Id. at 326. In Arizona v. Hicks, the Court held that an officer's movement of stereo equipment to view serial numbers constituted a search. Id. at 325. In that case, however, officers entered an apartment based on the "exigent circumstance" of the discharge of a weapon within the apartment. Consequently, a search was clearly involved because the officers intruded into an area in which the defendant had a reasonable expectation of privacy. By further moving the stereo equipment, the officers expanded the warrantless search beyond the scope justified by the exigent circumstances on which their initial entry was based. Id.