I'm listening to this free series on audible now. It's fascinating. He was convicted in France in absentia because Ireland cannot extradite a British citizen to France I think.
How did he know where to go, the day his friend (another journalist) tipped him off about the story, the other journalist thought it was a foreign woman. It wasnt confirmed she was French until 14.00 and by 14.20 IB was at her house in his professional capacity as a journalist and his partner was there with her camera. So he went there on a hunch? How did he know for certain where to go? He thought nobody would doubt a (fake) posh British journalist.
It is a fascinating case.