EWWWWW! Gave me shudders looking at those pics and thinking of poor froggy
. I agree its a tree snake, I've had those one's here as well they can get really dark olive on top almost black and have a yellow belly.
Do you have some numbers for snake catchers, it's probably a good idea to give one a call and get him relocated. He's definitely a good size for a tree snake tho. If you don't have any numbers the local police station often has a list if you wanted to give them a bell.