You keep asking the stupid question, "What is he hiding?", as if that's significant.Probably schedule A... who loaned him money and how much is he paying in interest.... But it's okay, just keep asking the same stupid question like Corky the Retard.Who knows? Until you get credible evidence of a tax related crime being committed, you won't know. But feel free to speculate.
And again, how do you expect to find if someone owes "The Russians" anything by looking at his tax returns? Which schedule shows that?
Here's a hint, Russian loans wouldn't show up on his personal returns, they would go to one of his companies. Is your view of the world really so simplistic that you think you would see "Loan from Boris to chase Moose and Squirrel" on his personal returns?