Federal agents had Michael Murray (defendant) and some of his co-conspirators under surveillance. The agents observed two large vehicles enter into a warehouse and exit about 20 minutes later. When the vehicles exited the warehouse, police observed inside the warehouse two people and a tractor-trailer rig carrying a long, dark container. The police subsequently followed the two vehicles, and when the drivers were stopped, the police found the vehicles full of marijuana. After hearing about the marijuana in the vehicles, the agents remaining at the warehouse went inside, where they saw numerous burlap-wrapped bales. Without touching anything, the agents left the warehouse, keeping it under surveillance while a warrant was obtained. The warrant application did not mention the prior entry and contained no information that was gathered upon that first entry into the warehouse. Upon obtaining a warrant, the agents reentered the warehouse and seized the bales, which were found to contain marijuana. Murray moved to have the evidence in the warehouse suppressed, arguing that the warrant was invalid because the warrant application did not mention the prior entry. The district court denied the motion, and the appellate court affirmed. The United States Supreme Court granted certiorari.