An Uber driver was trying to pick up a female passenger in San Francisco last week to be taken to Tiburon, where a man greeted her instead, the officer said.
The man told the driver that he wanted him to "give a box to the woman. After an hesitation, the driver agreed to do so.
Uber's driver put the box of sneakers on the floor near the passenger seat and headed for the place. Suddenly, as he was crossing the Golden Gate Bridge, the woman canceled the trip, leaving the driver with the mysterious shoe box.
Officials said a few minutes later, the driver had seen Marin County sheriff's deputies and asked them to help them examine the box. MPs found a pair of Nike sneakers inside, with "presumed fentanyl in the right shoe".
Authorities highlighted the sneakers - "the driver wanting nothing to do with shoes or drugs".
