The fourth week of witness testimony in Donald Trump’s hush money trial could be a doozy: Michael Cohen is expected to finally take the stand on Monday.

The long-anticipated testimony from Trump’s former lawyer and personal fixer would follow a breathtaking buildup by prosecutors of a case that ultimately hinges on record-keeping. Trump is accused of falsifying internal business records to cover up hush money payments that Cohen made as part of efforts to buy and bury stories that might hurt the former president’s 2016 campaign.