Kuklinski has been exposed as a liar on many occasions and by many separate researchers. He may have killed a couple people,but the rest is a fantasy sold to a gullible public by those with a vested financial interest in promoting this garbage.

My vote would probably go to Harold Strauss,one of the old Murder,Inc. guys. Better known as "Pittsburgh Phil",he is believed to have committed around 100 murders. Some unofficial estimates place his total at 400 or more,but there is no solid evidence for that figure.