Ex-House Speaker Michael Madigan is set to return to the stand Wednesday morning, continuing testimony that will surely be some of the most crucial and closely examined of the bombshell public corruption trial.

Madigan, the longest-serving legislative leader in U.S. history, was charged with bribery, racketeering, wire fraud, and other crimes.

Madigan is accused of leading a criminal enterprise designed to enhance his political power and enrich himself and his allies. Michael McClain, his longtime friend and ally, is also on trial and accused of acting as Madigan’s agent.