how to open locked icloud iphone4

If you do not know his Apple ID information, then you would need to try and bring the original receipt for the device and a copy of the death certificate to a physical Apple Store. They should be able to help you.

What iOS it is using is not important.

Unfortunately, no there isn't. It is about making a positive identification. This all has to do with trying to deter theft and the use of stolen products.