Originally Posted By: Camarel

I think it could've been either the thing i don't get is why did they not just kill him?


Good question. I don't think there is a definitive answer.
My take is that the only person that Luciano and Costello would have trusted 100% to handle that job (Anastasia) was already dead. There had already been a number of murders and attempted murders so why bring more heat on the entire organization by trying to kill Genovese.

But I think the biggest reason is that they knew that they could hurt Genovese more by putting him in prison for the rest of his life.

"When the snows fall and the white winds blow, the lone wolf dies but the pack survives."
Winter is Coming

Now this is the Law of the Jungle—as old and as true as the sky; And the wolf that shall keep it may prosper, but the wolf that shall break it must die.
As the creeper that girdles the tree-trunk, the Law runneth forward and back; For the strength of the Pack is the Wolf, and the strength of the Wolf is the Pack.