Use of a GPS device to determine the location of a stolen cell phone, thereby locating defendant, does not result in a violation of the Fourth Amendment. The two victims were walking in San Francisco when they were approached by a male subject, subsequently identified as appellant, who brandished a handgun and demanded their property. Victim 1 turned over his wallet but victim 2 threw her Prada purse containing a smart phone under a parked vehicle. Appellant retrieved the purse and fled. The victims were able to provide police officers with a description of his clothing. With the victim’s consent, Sprint activated the smart phone’s GPS device and the police were able to locate appellant. Determining that he had the purse, they arrested him. The court rejected appellant’s claim that his privacy had been violated by use of the GPS technology, finding that he had no reasonable expectation of privacy in the phone he had stolen. Whatever possessory interest he might have had in the phone was subordinate to the rights of the owner. The court’s analysis received additional support from Penal Code section 637.7, which provides that an electronic tracking device may not be used to determine the location of a person but then states that the statute does not apply to the lawful use of such a device by law enforcement or when the registered owner of a vehicle consents. Because police and an owner may cooperate to track a motor vehicle, it is unlikely that the state would be outraged but such cooperation to locate stolen property in the possession of armed robbers.