Father's fears as tug-of-love boy fails to arrive home
His Scottish father has now contacted a French police department that specialises in crimes against children in an effort to ascertain his whereabouts.
Vincent Ritchie told The Scotsman that even though he believes his son is being physically abused by a relative while in France, he is "determined" to keep his emotions in check and go through official channels in order to ensure his return.
The 47-year-old split with Guillaume's mother, Marylyn Muzika, six years ago. She was given custody of the ten-year-old and his French-born brother, Frederic, seven, at her home near the Belgian border.
Under the terms of their divorce, Mr Ritchie is granted custody of Guillaume during school holidays, and he was due to arrive on a BMI flight at Edinburgh Airport on Saturday evening.
Earler this year, there were emotional scenes as Mr Ritchie handed his son over to Ms Muzika.
Mr Ritchie had previously said a fearful Guillaume refused to board a plane bound for France, but the Court of Session ruled that he had breached international treaties on child abduction. Legal experts said the court would only have refused to return the child to France under extreme circumstances.
Mr Ritchie and his sister, Kriss, have won widespread support for their campaign to allow Guillaume to stay in Scotland, with nearly 11,000 people signing a petition.
However, they have expressed frustration at the inability of British authorities to help their cause.
"I'm very stressed and bewildered about what is happening," said Mr Ritchie, from Corpach, near Fort William. "It's now approaching 48 hours since Guillaume was due in Scotland, I'm getting worried. Gullaume has let us know he is still being hit by a relative."
Through a French friend, he has contacted police in France, who have made four visits to Ms Muzika's home, but there has been no answer. He has now asked the Brigade de Protection des Mineurs, an agency which investigated crimes against children, to investigate.
"Hopefully Marylyn has just locked up the children in the house," he explained.
"She is categorically breaking the law, and all you want to do is jump up and down and scream with anger, but it's in my son's interests that I remain calm, rational, and do things through official channels.
"I spoke to Guillaume on Saturday by telephone and it became clear from the way he was acting that his mother had no intention of sending him to Scotland."
Mr Ritchie's sister added: "The Court of Session knew this was a possibility, and we are holding them responsible.
"As far as we are concerned, this is now a missing children's case. Marylyn is in breach of the custody arrangements and it's sickening that the police in Britain are not doing anything. They should be getting in touch with Interpol.
"But we don't feel any surprise. Social services, the police, and justice system have all done nothing, and we just don't know what else we can do.".