Undeserving people receiving Zakah

Q: We know a man who is very wealthy; he is a millionaire and holds a prominent (Part No. 9; Page No. 435) position in society. He lives far away from my home, and I live in a village in the Western Province. Every year, during Ramadan, this man gives some of the Zakah on his wealth to the people of his tribe and he hands it over to a trustworthy person in the tribe to distribute it among the rightful recipients. The man entrusted with this job could not do it alone, so he asked me to help him to distribute the Zakah of this wealthy man. I agreed to do so and helped him to divide and distribute the Zakah money. However, sometimes, when I went to give the people their Zakah money, I found them either absent or dead, so I would take their share of the Zakah and add it to my share without them knowing and without the man I was helping or the wealthy man knowing. This story continued for three or four years, during which time I accumulated about 5,000 riyals. Please note that I do not know who the rightful recipients of this money are and I do not know their addresses. After this I sincerely repented to Allah and bitterly regretted what I had done, and from that time onwards I have led a righteous life - praise be to Allah. Now, I would like to give the people their financial rights, but I cannot tell the wealthy man or the man distributing the money about this, because I would be too embarrassed. It is also impossible for them to discover what I did.Your Eminence, I would like to know what I should do in order firstly to be free from this responsibility towards Allah (Glorified and Exalted be He); secondly to have a clear conscience; and thirdly to be free of my responsibility towards the rightful recipients of the Zakah. Please remember that I do not know who the rightful recipients are, because some of them are dead now and I do not know the others at all. Should I give the money I had taken as Sadaqah (voluntary charity), with the intention that its reward should go to its rightful recipients? Once more, (Part No. 9; Page No. 436) I hope you will give me a Fatwa on this issue.