JUDGMENT

And if he does it under a different nickname and IP address, will it be easier for you? :)

Let him suffer and change all his data every time. Until he starts playing fairly, but don't give him any slack, or other participants will be tempted to do the same.
P.S. Regarding this particular subject, I think either he will change his nickname (which I suggested to him) and play fairly, or he's a complete ...:D. You just need to see his moves.
I often regret that I don't have your ICQ.

Sincerely, LeSHiJ-MaX.