I'm sorry for my curiosity, but I really would like to know.

What happens to Žiga Željko in IOI 2015?

I remember he gets 100 in problem scales very quickly but not long after that, his submission becomes 0. In IOI stats page, his score are dashes (-).

I believe he is accused to be cheating. Can anyone (especially ISC, or those who attend GA) confirm this? What did he do?