Convicted of murder is not same as killing someonePaul Bernardo was convicted of committing several rapes and the three murders of underaged females in the Canadian Courts. The fact that his accomplice had a plea bargain allowing her criminal to be expunged means nothing.
Bernardo will not be given a retrial to prove your claims that he is not a murderer as the evidence against him particularly on the videos alone was enough for the murder convictions to never be over turned.
eg if I stab someone and you stab someone, only one of us actually killed the person (fatal wound) but both of us are convicted since committing a criminal act makes you liable
As for retrial Bernardo already made the claim all killings were by his wife; but by this point the Crown already made the plea so its a moot point; Karla will never get what she deserves