My mother's friend is a huge cat lover and often takes in strays. One day, one of her cats, Henry, ran away. When he didn't return, she went out to look for him. She looked for days and days and put up posters. Still, Henry didn't return and she gave up.
Months later, she looked outside to find a small, thin black cat roaming about on her lawn. It was Henry, thin, dirty, and fleabitten, but very much alive. She still has Henry to this day and he's fat and happy.
Have faith, cats are smart. He may not come back immediately but there's a good chance he will so keep looking. I'm sorry about Max and I wish you good luck!