Hubert Caouissin admitted to killing his brother-in-law, Pascal Troadec, along with his wife Brigitte and their two children age 18 and 21, after becoming obsessed with the idea that they had gold stolen from the Nazis hidden in their basement.
When the Troadec family seemingly disappeared without a trace in February 2017 the case hit a dead end until traces of blood and DNA were found at the house which had been left "frozen in time," according to police.
It was not until three weeks later that Caouissin confessed to the murder while in police custody following his arrest due to traces of his DNA being detected at the scene.
Police pressured Caouissin into providing answers and he subsequently explained how he had carried out the murder and the disposal of the bodies.
Caoussin had grown obsessed with the idea that his brother-in-law's family was hiding gold coins and bars originally owned by the Nazis during World War Two, and he believed that he too should have been given a share of the wealth.
On the evening of the murders, Caouissin broke into the Troadec's house intending to steal a key to the basement where he claimed the gold was hidden. When entering the house, however, he unintentionally woke the couple who went into the hallway to see what the disturbance was.
Caouissin then attacked and killed Pascal Troadec and his wife with a crowbar, and then murdered their two children in the same manner, before enlisting the help of his wife in order to dispose of the bodies, which he dismembered in an attempt to make the crime untraceable.
Psychological reports publicized after the arrest suggested that Caouissin was suffering from “extreme paranoia” fueled by the feeling he was being lied to and cheated by his family members, although his mother told the French news that she, along with her relatives, "doubted [the gold] ever existed."
Although he faces life in jail, Caouissin's defense team hope to convince the court that he was psychologically unfit at the time of the murder, thereby avoiding the maximum sentence.A similar ruling was made at the trial of Kobili Traore who was found guilty of killing Sarah Halimi, a Jewish French woman, also in 2017.
“He never intended to kill the family,” Caouissin's lawyer told the French press.