Check your luggage before boarding and don’t leave your luggage unattended when going to foreign countries.
I’ve heard of cases where the person went to get something from the airport commissary and they were gone long enough to have their luggage compromised.
My crew and I flew all over the world. We would always have someone standing by, keeping an eye on our luggage while it was being handled by someone else be it the van driver or handler or even the bellman. ALWAYS.
Did you pack your bag. Think hard before you answer that question.
I can understand a few ounces going unnoticed but not 15 pounds!