Last Riddle of the Day..?

On 17 Dobson Street, Perry Owens owned a brass music store. Next to him, there was another woodwind music shop owned by Jeffrey Flanagan. One day, two kids named Milo and Spencer went into one music shop and then the other looking for an instrument. A couple of days later, an instrument went missing. The police were put on the case. The next day they found a clarinet in the deserted alley on Harlem Avenue. Both music store owners immediately told the police that it was their instrument. The chief of police told the officers to give it to Jeffrey Flanagan. What made the chief so sure it belonged to Jeff?