Have read the posts of the past day with interest, especially from those with closest local knowledge.
If that creek or 'underpass' are so hard to access and there are signs on walls etc, if just floors me even more that the brother would think of looking there himself and, lo and behold, find Amesha in that very place.
Taken at face value, if she did not return from buying butter and milk, wouldn't you assume she might have had an accident, been hit by a car etc etc - and perhaps called the hospital or something?
For the brother to look there in the creek, first thing in the morning, indicates to me that he must have been quite familiar with that spot himself. And what does it infer in relation to Amesha's fate? It seems like an unlikely place for someone, who was not familiar with the complex, to take Amesha to. At first I thought the brother might be suspecting Amesha had sought to end her life, and had looked there for that reason (even though, indeed, there might have been more straightforward ways for her to commit suicide). Yet he tells media that she seemed happy...
As for him making that blood curdling scream ... Doesn't sound like the usual reaction of a man, somehow. It's like he wanted the world to know he'd just 'stumbled across' something that was, to him, horrifying.
And back to that thing about the gift cards. I appreciate that English is his not his first language and that the intention of some of what he says may get skewed through media reports etc, but what's the significance of buying milk with gift cards? Why would you even mention that? Was the family in financial trouble, to the extent that they did not have a few dollars between them to buy milk and butter with? You can go to Coles and buy whatever little you want and still put it on a credit card, if you don't have the cash...
One poster earlier on mentioned the possibility of a secret affair coming into play. That thought had crossed my mind, too, but I didn't know how to reconcile that with the goings on of that evening. If you wanted to meet up with someone for a tryst, you'd think it'd take you longer than the time it takes to buy milk and butter?!
I'm sure the police know much more than they are letting on. For starters, whether the brother has an alibi and when he came home from work, and whether or not Amesha had the car at her disposal or the brother had taken it to work.