blackthrow or svartkast is a term for a device left behind in potentially hostile territory to continue operating until it is discovered or fails
Then when you walk around, sit in the food court eating, or if the device is close to the outside, sit somewhere out of sight of the cameras with a strong wifi antennae and grab whatever data.
Unless they have some "free" wifi that the device could hop on to send it to some server somewhere.
Using that and / or 4g would make it easier to find the device and, of course, the person though.