Talk to him. Don't yell. Don't get all crazy and make yourself look out of control. Let him know you are disappointed in him because you thought he knew right from wrong and you expect such awesome things from him! So what's up, boy!?
STEALING!? Wow....smh....I never thought you were a thief.
Things like that. Make him SEE your disappointment. Make him know he blew your trust. BUT...let him talk. LISTEN. it's deeper than the money. For sure.
What does a belt whipping do? It just teaches him to take a beating and shut up about how he feels because dad doesn't give a crap anyway. He's 9...not 16. Or explain that the punishment for this is a whoopin...so that's what he's going to have. DO NOT DO IT WHEN YOU ARE ANGRY. And don't use anything but your hand, if that's how you plan to take care of this.
But...in my experience with this age, when they do sometihng like that, they want you to LISTEN to them. He denies because he knows you'll get crazy and won't LISTEN.
He's your boy. He's not his brother. Raise him to be the type of man that is honest because he understands why that's important...not someone who lies to get out of trouble.