Who was the bow-tie wearing NOI cat that shot up Stringer Bell?

[TraceOneInfinite]

I was kind of confused the whole season with his character.  First he is looking for Omar for some reason, then after holding Omar at gun point he ends up joining Omar, then he meets up with Avon Barksdale at the Barbershop like he wants to kill Avon but Avon offers him money or something and then Omar and the "bow tie" go and kill Stringer Bell.

So who was the bow-tie wearing NOI cat, could somebody explain that whole part of the story line?

[Javier]

Avon hires Brother Mouzone to protect his crew from Prop Joe's crew.  Stringer had an agreement with Prop Joe, so Stringer tells Omar that Mouzone was the one responsible for killing Omar's BF.