...to the murder.

There were a ton of witnesses who were in the bar/restaurant when Billy was breaking Tommy's balls, and witnessed Tommy flipping his fucking wig. The next day, Bats comes up missing. Not a huge whodunit. They probably suspected Jimmy and Henry were involved, but had nothing to back it up. Now, I would imagine that a crime family doesn't always require incontravertable evidence to wack someone, but Jimmy and Henry were still top money-earners for them.