A shooting was reported in an apartment building. A bullet fired through the floor of Hicks' (D) apartment injured a man on the floor below. Officers went to D’s apartment to search for the shooter, weapons, and any victims. They found and seized three guns and a stocking-cap mask. They also saw expensive stereo equipment, and the officer had a reasonable suspicion that the equipment was stolen since it was out of place for the rundown apartment. He moved the equipment around to search for serial numbers, which he found and called in to his headquarters. It was confirmed that the items had been stolen in armed robberies. D was arrested. D was subsequently indicted for the robbery, but the state trial court granted his motion to suppress the evidence that had been seized, and the Arizona Court of Appeals affirmed. A warrantless search must be 'strictly circumscribed by the exigencies which justify its initiation,' and the policeman's obtaining the serial numbers violated the Fourth Amendment because it was unrelated to the shooting, the exigent circumstance that justified the initial entry and search. Both state courts rejected the contention that the policeman's actions were justified under the 'plain view' doctrine. Arizona (P) filed this petition.