Hubert Caouissin, 50, was sentenced to 30 years in prison for the quadruple murder of the Troadec family in 2017.
A man in France has been sentenced to 30 years in prison for murdering four family members, who he believed to be hiding gold bars.
Hubert Caouissin, 50, had admitted killing members of his family at their home in Orvault, near Nantes, on the night of 16 to 17 February 2017.
The victims were his brother in law Pascal Troadec, his wife Brigitte, and their children Charlotte, 18, and Sebastien, 21.
His former partner, Lydie Troadec, 52, was sentenced to three years in prison, including two years for altering the scene of a crime and receiving a corpse.
She was imprisoned after the hearing.
Caouissin was convinced that Pascal Troadec had stolen a family treasure of gold bars discovered in Brest, a remnant of the gold of the Bank of France hidden from the Nazis, evacuated to Canada at the beginning of the Second World War.
He claimed he went to Orvault to gather "information" about the theft of this imaginary treasure, and maintained he had killed his victims to defend himself.
His lawyers had asked the jury not to sentence him to life imprisonment and to grant him the mitigation provided for in the criminal code in case of impaired judgement.
Thierry Fillion, one of his lawyers, said Caouissin suffers from a "chronic paranoid delusion", unanimously recognised by psychiatrists and psychologists.
After killing his family members with a crowbar, he had then cut up the bodies with a kitchen knife over the course of three days, attempting to get rid of the evidence of his crime.