Last night, I and a few of my friends received a message from one guy begging for help in his private contest. It seems to me that he used many accounts in order to avoid getting punished.
You can see his profile here: I_Love_Heisenberg_.
(this is the only account which is not unrated)
After having examined his submissions, I found out that he has been cheating for a long time.
As you can see, many of his submissions have been skipped.
I suggest banning him permanently for the good of other users.