I Missed the Whodunnit

I was watching "Maigret and the Man on the Bench" last night, which is an hour-and-a-half-long mystery with no commercial breaks. Toward the end of the show, I was getting hungry, so I decided to make some cinnamon toast. I thought I had enough time before the climactic scene to toast my toast, but when I walked back to the TV, the credits were rolling.

So, if anybody knows why the boarding house/brothel owner and the man with the canaries conspired to kill the man who sat on the bench, could you please explain it in the comments?