I honestly doubt about luggage thieving in Doha Airport.
It could be elsewhere, any transit or even at home.

I had one friend working in one airport and he told me that luggage handling ppl is quite habil opening locks without forcing. The normal place to make it is while boarding the luggage on the plane, as there is nobody watching inside the "tummy" of the airplane.

But again, I honestly dont think it happened in Doha Airport, too risky for this poor people as per the high price they have to pay if catched.

By the way, I remember one time when arrived home, that when I open my luggage I found a nice A4 paper inside written as: "Luggage checked in Munich Airport" (my transit airport)

Remember that in some countries, in some airports authorities are allowed to open and check your luggage even without your presence.

War looking for peace,
is like fornication looking for virginity.