How to factory reset a locked iPhone that is not mine?

I found an iPhone on the street and honestly did everything I could to return it to its owner, it's an old 4 so the person didn't seem to be using find my iPhone or try in any way to contact the phone and reclaim it. A while has gone by and I recently broke my phone and would like to set up this new phone in my account if possible. How can this be done? I don't want Apple to think I stole it, and when I try restoring it on iTunes it seems I need the owners information. Any help is greatly appreciated!

If it isn't locked then you should be able to connect it to iTunes and factory restore it on there. Now if it is locked then I don't think you'd be able to do that because it would tell you to unlock it first. Also if they reported it stolen/lost then i think the company would have it set in as a bad ESN and I don't know if you'd be able to set it up in your account. But you may be able to put your sim card in if you have one.