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iMore Question
Bought a used ipad. Ended up being stolen. Called police but it was not listed as stolen and the number on ipad to contact owner is not working number. How to get ahold of the owner ipad locked
You can use Find my iPhone to track it down at https://icloud.com , but you will have to keep checking till the person connects to wifi. But in the case you have a passcode on the iPad, you have no luck.
You might try Apple also, they may be able to contact the owner, IF they have registered their device.