Sources on the French side of the team investigating the murders say it is a matter of asking questions of Zaid Al-Hilli on his feud with his brother, their father's inheritance and their father's money in Switzerland.
He is in custody as a result of moving from being a witness to a suspect. We are told they have no more elements of proof at this stage.
On Wednesday it was made very clear that Zaid Al-Hilli was not a suspect, although I was told "this could change at any time".
More top news
Thousands of pounds of NHS cash is being spent on holidays, aromatherapy and even summer houses for patients, according to research
Welfare reforms do not lead to more people being in work, a new study suggests.
A new vaccine to protect young children from meningitis is to be offered across the UK from today.