Yesterday's testimony by William Taylor, the US emissary to Ukraine, laid out a clear, detailed timeline. Michael Isikoff, chief investigative correspondent for Yahoo! News, says it's time to open the hearings up to the public. 

In his testimony, Taylor described "two channels of U.S. policy-making" in Ukraine, official State Department and security channels, and the "highly irregular" efforts by others in the President's circle to undermine the longstanding policy in Ukraine. Taylor laid out the most complete timeline of those efforts available thus far, and cited contacts he'd had with others that indicate President Trump's direct involvement.