I'm sure a lot of guys in Brooklyn suspected he may have been a rat. But because they knew he was a half a nut job lots of guys also feared him. So they kept quiet.

I believe that may be the "true" reason why Greg's brother Sal Scarpa was set up and killed. Because he may have found out about Greg and confronted him about it. Or was threatening to tell the borgata. (my personal opinion on this matter). In my own mind I wonder if Greg killed his own blood to keep that secret...He never made an inquiry, or a squawk about Sal's death. I find that a bit strange.