Just maybe, maybe, maybe, he is innocent, but has as much faith in the law as I have. In a foreign country which has already found him guilty of murder in the press, informal media, and in the coronial report, he probably doesn't fancy his chances in a trial. The safest way out may be what he is doing. Eighteen months vs 20 years sounds like a no brainer to me. Recently an australian was arrested in Bali and to expedite her release and return home she, likewise, pleaded guilty on the assurance there would be no jail time. I think when you are facing the crap-shoot of a trial, you play the odds and take the risk you are comfortable with. Manslaughter just means he failed to rescue her, not that he actively mudered her with intent eg. pedestrian runs in front of your car you're guilty of manslaughter. The case can't be that good if the prosecutor accepted the plea, he also took the best odds from his point of view. If he was confident of a murder conviction he would have insisted on a trial. There is no absolute truth it's just relative to where you are!