Congressman Tim Walz says he'll take part in a Congressional hearing to investigate the Wall Street abuses that potentially caused the financial meltdown.Walz serves on the House Agriculture Committee, which will hold the hearing examining the role credit derivatives played in the financial meltdown.((44.50))Rep. Tim Walz says, "What needs to happen, and what I'm still convinced of is, the free market has to function correctly. But to do that we need rules to play by. And we're out there to try to make sure that oversight is put in place."Walz hopes the hearing will start the process of determining what kind of Wall Street oversight must be adopted to make sure this kind of financial crisis never happens again.Tonight at Ten, we'll take a closer look at 'credit derivatives' and what role they may have played in the economic crisis.