I don't know what the apple id is for an iphone I have. Is there anyway to access the device?

What happened:
At school I leave my locker unlocked all the time because I have a faulty lock and im too lazy to get a new one. This morning (Saturday) I open my smaller pocket at the front of my school bag, like I do every day, and i found a black iPhone 5s. The phone's screen is pretty badly cracked, the phone also hasn't been used for about 45 days because there was a notification on the screen saying 45 days. The phone's service has been turned off (No Service) and it was dead flat when I found it. I thought that someone psrobably dosen't want this phone then? I mean they went to all that trouble just to put it in my bag? So I decided to wipe it clean considering there was a passcode. I can't get into it anyway because I don't know the owner's apple id.

Should I just hand it in like I was originally planning to?

Read more: I don't know what the apple id is for an iphone I have. Is there anyway to access the device?