Hi Lesley,
I worked for Corrections Victoria and unfortunately you don’t have many avenues.
(Here in Victoria) If you call a prison and ask if a person is in fact incarcerated they call taker can only confirm or deny if the person is in fact held in custody, "however" they are NOT permitted to tell you which prison the person is in.
So you can in fact confirm that he/she is in custody, just not where.
In saying that there are ways to work out where they are "likely "to be. For instance, here in Victoria every male held in custody will firstly go to the M.A.P to be assessed. They are then sent out to and appropriate remand prison. Most go to the M.R.C but high profile may go to some of the other bigger max security prisons in the state.
So here in Vic if they have only been in custody a short while, say a few weeks, they are likely to still be at the MAP but if its a bit longer then they are probably are at the MRC etc.
I know its probably not what you are after, but hope it helps anyway.
Thanks for the comments in your newbies Post recently.
Krusty