Gilletti, an undercover officer, arranged a heroin 'buy' with one Patricia McCafferty (from whom he had purchased narcotics before). McCafferty told him it would cost $115 'and we will go down to D’s for the dope.' Gilletti notified his superiors of the impending transaction, recorded the serial numbers of $110 in marked bills, and went to meet McCafferty at a prearranged location. She got in his car and directed him to drive to 2311 North Fifth Street, which, as she had previously informed him, was D's residence. McCafferty took the money and went inside the house. She came out and got into the car. Gilletti asked for the heroin. She extracted from her bra several glassine envelopes containing a brownish-white powder and gave them to him. Gilletti placed McCafferty under arrest. He told her that the police were going back to 2311 North Fifth Street and that he wanted to know where the money was. She said, 'D has the money.' Sergeant Pruitt and other officers came up to the car. Gilletti showed them the envelope and said: 'D has the money.' Gilletti then took McCafferty to the police station. Pruitt and the others saw D standing in the doorway of the house with a brown paper bag in her hand. They pulled up to within 15 feet of D and got out of their van, shouting 'police,' and displaying their identification. D retreated into the vestibule of her house. The officers followed and caught her in the vestibule. The bag tilted and 'two bundles of glazed paper packets with a white powder' fell to the floor. Alejandro, who had been sitting on the porch, tried to make off with the dropped envelopes but was forcibly restrained. D was told to empty her pockets. She produced $135, $ 70 of which could be identified as Gilletti's marked money. The white powder in the bag was later determined to be heroin. McCafferty pleaded guilty. D and Alejandro moved to suppress the heroin and money found during and after their arrests. The court held that D's 'reentry from the doorway into the house' did not support allowing the police to make a warrantless entry into the house on the grounds of 'hot pursuit,' because it took 'hot pursuit' to mean 'a chase in and about public streets.' The court did find that the police acted under 'extreme emergency' conditions. The Court of Appeals affirmed this decision without opinion. The Supreme Court granted certiorari.