Aww that's so sad. I hope you get him back soon. Don't give up hope just yet though. You say he went missing on 12th? Well our last cat went for missing for over 10 days a couple of years ago. After spending night after night with the windows open hoping she would come back. We gave up, closed the windows and went out. Later that night, we were listening to some music and I heard the faintest meow at the window, and there she was! Cold, hungry but safe and well. I took her to the vets and she looked at her claws. They were all worn down and the vet thinks she was trapped in someones shed or garage the whole time.
Call all the local pet resuce places and put a picture up in your local vets. Your cat may have just wandered away and got lost so someone esle is feeding him or he could have got scared and hid in someones garage or shed. He is a gorgeous little thing so someone may have found him and taken him home. They may not know that someone is looking for him.
Good luck and I hope you get him back soon!