Cesare runs, but he is short and the door is locked. It doesn't take long for Surdrak and Naga to catch up to him. As Surdrak lands, the shadows rise around him to loom over Cesare's head. And although Naga is short, so is the dwarf, and so the basset hound doesn't need to look up far to meet Cesare's eyes and snarl.

Cesare can't stare them down. Instead he spins around, wild-eyed, to face the other senators. "You're going to listen to them? Over me? Cesare? I have been in this senate chamber since the founding of Runite!
I have seen this city grow! And I have seen it debase itself! You mean to tell me that you will allow these--these mercenaries, these murders to lie and believe their lies over my words? That you will allow...subhumans to walk proudly among us?!"

Leif shakes his head. "Cesare, stop talking. Have you lost all sense of decency to your greed?" He nods to the halfling and Artorias. "Fix the document, in front of us. Then read it."

They do so, over Cesare's screaming and protests that grow to the point where he has to be escorted from the chamber. And the document reveals a plot. A contract between Cesare and Avir, detailing how they would divvy up tribute to Avir and how Avir would help consolidate Cesare's hold on the city.
It doesn't go into how Avir caused the plague but more describes their "business partnerhip" once Deirdre and her sewer system and riches are out of his hair. And it leaves no doubt as to who caused the cholera epidemic that swept through the city.

Things happen very quickly after that.