How about this:
When it was time for the prisoners to speak, Cain rose on their behalf. “I know that many are angry about the events of last week, and with good reason. But before passing judgment, I ask the Senate to consider our motives. We did what we did not for personal glory but to usher in a new era of power and prestige for our world as the crown jewel of the Imperium.”
“With a felon as governor!” someone snorted.
The chamber erupted with laughter.
Joseph watched Cain closely. Sweat beaded on his upper lip. He’s desperate.
Cain pressed on. “As a member of the Imperium, we could use our influence to turn it away from its pagan gods toward the only true faith — Christianity. Jesus said, ‘Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost.’ Fifty billion souls wait to be saved across the galaxy!” With a crafty look in his eye,Cain drew himself up to his full height. “We here offer to leave our beloved world forever so that we may serve our Lord!”
The chamber exploded with outrage.
“Blasphemer!” many yelled.
“Murderer!” others called out.
“Hang them!” several cried.
Joseph shook his head. No contrition. Still, points for creativity.
Is the bold part required? I think that makes it clear he's lying, but I'm not sure if I need to hit the reader over the head with it. After all, I remind the reader he's a felon, a mass murderer, desperate, and "creative".