The Senate trial is officially underway, with the Chief Justice and members of the Senate sworn in this week. But in a last-minute addition to the evidence, an associate of Rudy Giuliani gave the House of Representatives documents that shed new light on the Ukrainian pressure campaign. Parnas, who is out on bond on federal campaign finance charges, also spoke publicly this week for the first time about his involvement in the scheme. Josh Lederman, national political reporter for NBC News, explains what we learned from Parnas, the credibility of his allegations, and how this new information could influence the Senate trial. Have a question about the Senate trial or something else impeachment-related? Email our host Steve Kornacki at [email protected]. Further ReadingKey things we learned from Lev Parnas' revealing MSNBC interviewGiuliani associate Parnas says Trump 'knew exactly what was going onIndicted Giuliani associate Parnas says Trump ordered Ukraine ambassador's firing several times before recall