The provided Recapy context is only metadata-level and does not say who actually killed the casino mogul. I don't have the killer's identity in the retrieved material.
If you want the reveal, tell me "Spoilers OK" and I will provide the spoiler (or you can paste/upload episode/chapter text or a trusted summary and I'll extract the answer). Otherwise I can give a non-spoiler summary of the show so far.
Sources
Provider metadata
Tap to read source excerpt