Walk away when he screams at you. Apply consequences consistently. Don't threaten him with a consequence you can't confirm or follow through on. What's good for his brother is good for him. Don't rely on his testimony alone.
Parents find a series of half-truths and whole lies whenever they check their kid's story.
Check when he's supposed to be at his friends. A good idea is to check on your kids in the middle of the night. They don't remember lies. At least, check things out every so often. Don't allow evasion.