From The Washington Times :
Mr. Rosenzweig said the committee  has moved beyond hearings with academics debating the merits of impeachment and instead has called primary witnesses such as former White House counsel Don McGahn and former Communications Director Hope Hicks.
“The shift in tone is also a reflection in shift in focus away from laying the legal groundwork and towards doing the factual digging into what exactly happened and then obviously what that means,” he said.
- “The Washington Times”: https://www.washingtontimes.com/news/2019/sep/2/donald-trump-impeachment-push-picks-steam-during-c/
- “committee”: https://www.washingtontimes.com/topics/judiciary-committee/