I think my brother's stole money?

Money has went missing from my mum's room and my little brother has just came in with a new iPhone 6, he says his girlfriend is letting him use her old iPhone. I feel like he might of stole the money and bought a iPhone but I've checked the warranty on the iPhone and it ends October this year so he might not be lying or he might of bought the phone second hand. I don't want to blame him for it unless I have proof. Can anyone think of anything I can do

Try talking to your parents.

You're not blaming him if you just ask in private. He might feel like you're accussing him but just say that you're concerned. If he tells you the same thing again, and you still have that gut feeling then tell your concern to your parents and ask his girlfriend.

Ask his girlfriend if what he says is true.

Check with his girl friends mom. See what the truth is about the phone.