Black Listed upon transit arrival at Doha Airport

Hello All,
I am seeking advise regarding Transit for connecting flights. I have been living and working for a period of 6 months in Doha in 2012', short period because my high profile sponsor and partner had cheated me and after consultind with a lawyer in Doha he'd recommended me to not pursue legal actions that may backfire to me due to that I will be dealing with a high profile Qatari individual. So I had my exit permit and left the country as per the lawer's advise.
Months later while abroad I came accros this Qatari individual who has threaten me and accusing me with untrue accusations as it was his excuse for his actions, telling me that if I go in the future to Qatar he will make anything possible for me to get problems in there.
As I may need to travel with Qatar Airways and be upon arrival on transit for my connecting flight, my question is how could I find out if this man has made something for me to be black listed in the immigration or police authorities in Qatar, I must comment that during my time in Qatar I did not engage in any financial loans or any legal problems.
I will thank you for your advise.
If you are in transit, there is nothing he can do. All his threats are meaningless. He will possibly not even come to know that you are passing through Qatar. During transit, you do not need to go through immigration.
Joe, No need to fear, that guy will be sleeping , you can pass peacefully my dear , good luck .......
As long as you are in transit only your hand baggage will have to undergo a security check.