Q: hello, my iphone is icloud locked? with the id i cannont get access becauis in is not mine, i get this device aftermarket

hello, i buy this used iphone 5 with ios 6 and can use it for several hours , till i start ios 7 update. i didn't know that it can be locked by find my iphone program. I'm new to use iphone. but as i understand later, it was. now i cannot activate it and also i cannot contact with the seller to ask him for his apple id, his phone number is offline. i have the original box and serial DN******TTP.

ask for activaiont help and erase my iphone from find my iphone, thanks

<Edited by Host>