Thats a season 2 spoiler USA, as is what follows.
He knows who killed Jimmy though, he said to Nucky earlier in the season that he didn't mind because it was all part of the business and Jimmy had plotted against Nucky etc (all in the game yo). Said he killed Manny Horowitz because killing Angela was not part of business, she'd nothing to do with it.
The thing about Cromwell and Stephen Root is they are both great actors but still couldn't lift that bullshit.
