There's plenty of evidence. One witness claimed that he saw Lewis stab someone, the suit that he was wearing at the time was never found, one person's testimony changed over time in Lewis' favor, he was convicted of obstructing justice for giving false statements to police following the murder, and the case didn't go forward only because he agreed to flip on the other two people in exchange for a lesser charge.
Leonard Little drove drunk, killed a woman, then drove drunk again to prove that he wasn't remorseful for it. Having the venomous opinion of Vick that you have is fine- that's absolutely your right, and I don't really even disagree with you. I just can't figure out why guys like Lewis and Little are spared from similar wrath.