Well I'm starting the investigation from the different angle
- two people that I have always considered crystal clear are Julien and Laurence, I still can't see anything wrong with Julien but looking at Laurence now....
First thing is that she recently had a child and explained to Julien and Tony that now she felt ready to start family (maybe it's to do with Ian declared dead???) she speaks very good English - it's probably nothing but maybe she is MOLLY...... Ian always painted Molly as a little child but some photographs show her a bit older and I had impression that she run away from the house, let's say when 14 years old. Maybe Ian never even abused her but she discovered who he was and didn't want live pretend life like her mother.
With some help from friends, long distance relatives etc. etc. she ended up in France. Became policewoman to fight crime, abuse.....
Now she doesn't want contact with her parents, feels sickened by her mother covering for Ian and never wants to see them again.
Ian loves Molly and wants to find her, starts searching (maybe that's why he sympathises with Tony when he starts his search and offers money for reward). Finds Molly now Laurence and they somehow manage to rekindle their relationship (blame it all on the mother...) and Laurence starts to support Ian ( which might explain his contacts in police station) and maybe cover up for him....
Not sure what else......
. and how it all links to Ollie.