Here's my theory for the two cars seen at Kholo. Which is the first thing I've been able to come up with that provides a decent motivation for accomplice involvement. The way I see it, unless a 2nd person was involved in murder planning or discussion from the start, it still seems a bit of a stretch to call up a lover or relative late at night to help dispose of a murder victim.
(1) Perp goes out into bush - leaves car lights on for illumination while dragging body down to river.
(2)Flattens battery (or something else that stops car starting - wet distributor?).
(3)Has to call for help at this point, cos otherwise he's stuck in very compromising situation - HAS to get out of there. Can't call RACQ, no way to do it alone. Calls for help with breakdown story.
(4)Person comes out to help, maybe for some reason they can't jump start car(no cables?) but has to tow back instead?
(5) Eventually gets home and is able to charge battery (maybe jump leads are in other BC car) so when police turn up the next morning, car is charged and they can drive it off for testing ok
So accomplice may not have helped with body at all, but just went to help with car breakdown. They'd see through the story soon enough, but there are reasons for them to just go along with it for the moment:
(a) you're out in the bush alone with guy you realise is a murderer - only sane choice is to help him and stay in his good books until you get back to town
(b)you don't realise what was happening until a day later when he reports wife missing, then you suddenly realise what he was doing out there, and that you're now an unknowing accomplice, having already given significant assistance?
And then even a quite innocent person can be in a dilemma over what to do next, since you'd just helped cover up a murder.
And a less innocent person might have financial motivations, eg Ali's death will cause financial dramas and if it's found to be murder the life insurance will not be going to the original recipient. Other family members' home was mortgaged for business loan so if all that falls through there's quite a motivation for family to help cover up.