The front company all this money was funnelled through? All County Building Supply and Maintenance which did nothing more than inflate the value of transactions.
I suspect what Mueller will find (if he hasn't already) is a long financial relationship with Russian contacts leading up to the election. This of course included Flynn, Manafort and others who profited from Trump's arrangements. This undoubtedly includes Don jr. and Jared Kushner.
With Trump's poll numbers tanking in every state in the union he had better hope the GOP retains the House and Senate. Otherwise it's going to get very uncomfortable for the Donald.