Some theories are:
1. Marion answers Le Courrier ad.
- He stalks her and steals her wallet to see if she has anything worth stealing.
- He starts a friendship with someone at her bank to get assets info.
- He continues stalking her and realises GE is always at her house.
- He keeps an eye on her from time until she's single.
2. He reads a lot of newspapers so he sees Marion won an award.
- He's obsessed that she is a teacher and soccer star's ex wife, like MC.
- He stalks her and realises she's single and has assets to steal.
3. He sees her at Art Centre because he hangs out there trying to spot appropriate victims.
- He stalks her and realises she's single and has assets to steal.
How silly. Just realised we can discount the idea she replied to Le Courrier, and then he stole her wallet to suss her out. Wallet was stollen first, then ad was placed.
The only way he could have stolen her wallet in 1994 is if in the months after he returned to NSW from Tas and she settled into Southport, he randomly spotted her, or someone tipped him off about her.
Theories update
1. Marion answered Le Courrier ad, he stalked her and waited until she was single.
2. He randomly stole her wallet OR was given info about her from bank or real estate and then stole her wallet.
3. He saw her award in the paper and became obsessed due to similarities with MC.
4. He met her through arts centre or school, either randomly or was tipped off.
I still think it's possible that RB had a friendship with the dodgy real estate agent OR bank employee (most likely bank due to the suspicious withdrawals later in timeline), and they could've informed RB when a single and vulnerable women bought a house and had assets. IMO.
But which theory is most likely?
We know RB doesn't pick victims at random, he plans ahead to make sure they have assets and are vulnerable.
He targeted GGB because she was single, owned a house and ran her own business. He targeted JO because she was getting divorced, a house and a settlement. He targeted MC because...??? We don't fully know. Perhaps he had envy or a grudge against FR and that turned into an obsession with obtaining MC? Or MC might've just been a wealthy divorcee target like JO. We don't know.
It is very possible RB saw MC in 1992 (thank you
@BonnieB)
RB said he was in Luxembourg between 1981-83 with his family running the family business. That is when he allegedly met FR and MC as they went to RB's shop together. We might assume FR and MC were married at the time, right?
So it's possible FR and MC were separated by 1992 when RB went to EU. Perhaps he chose MC as a victim in the same way he chose JO... as soon as he heard they were getting divorced, he suddenly appeared. Just a thought.