Humphreys was a Top Echelon Outfit guy. He could never be one of the top three because he wasn't Italian. Other than that, he was the top guy. He was also in charge of all the non Italian guys. Alex, Pierce, Kruse etc. were all partnered with him. They were his crew. He was like a Capo and those guys were like made men who were with him. He was brilliant and very well respected.
He dealt with all the other Capos and made men in the Outfit directly when needed. I do not believe he killed anyone, but I could be wrong.