A French murder trial that opened Monday has transfixed the public because of the mystery at its core: where is the victim's body?

Cédric Jubillar, a 38-year-old painter-decorator, is accused of killing his wife Delphine nearly five years ago in a fit of jealous rage.

He has always denied the charges and, other than circumstantial evidence, investigators have struggled to build a case. There is no body, no blood, no confession, and no witness.

With its unexplained central fact and its cast of characters from small-town southern France, the affair has become a social media sensation.

Self-declared investigators have set up countless chat groups where they swap theories and share testimony – much to the irritation of police and families.

These groups are the equivalent of the bistro counter – but with more people, said psychoanalyst Patrick Avrane, author of a book on attitudes to crime.

Everyone constructs the theory that suits him or her the best.

The Jubillar mystery began at the height of Covid lockdown when – in the early hours on 16 December 2020 – Cédric Jubillar contacted the gendarmes to report that his wife had gone missing.

Delphine, who was 33 at the time, was a night nurse in a clinic not far from their home in Cagnac-les-Mines in the south-western Occitania region. The couple had two children, aged six and 18 months.

Police came to understand that the Jubillars did not have a happy relationship.

Cédric Jubillar was a habitual cannabis user and barely held down a job. Delphine was in a relationship with a man she had met over the Internet. She and Cédric were talking about divorce.

Police and locals conducted extensive searches in the surrounding countryside – with potholers descending into some of the disused mineshafts with which the area is dotted.

Delphine's body was never found, but gradually a case was built against her husband, and in mid-2021 he was placed under investigation and detained.

The prosecution at the trial in the town of Albi will argue that Cédric Jubillar had a clear motive to kill his wife because of their impending split.

Lawyers will raise other points: certain odd actions by Cédric on the night of the disappearance; signs of a fight, including a pair of broken glasses; a neighbour who heard a woman screaming.

Cédric Jubillar's own character will also be scrutinized, with witnesses expected to describe his threatening behavior towards Delphine before she disappeared, and his apparent lack of distress afterwards.

Two of his acquaintances – a former cellmate and a former girlfriend – will reportedly cite that Cédric confessed to the murder and indicated where her body was.

However, following further investigation, no body has been found, leading the defense to challenge the reliability of these testimonies.

Moreover, Cédric Jubillar's case hinges on the absence of concrete proof linking him to the crime, despite the public's perception of him as the prime suspect.

The trial is expected to last four weeks, with 65 witnesses and 11 experts scheduled to take the stand, resulting in over 16,000 pages of evidence presented.

Public interest in the case can be attributed to its resemblance to a crime novel, as noted by writer Thibault de Montaigu in Le Figaro. The enigma surrounding the case stimulates thoughts about how a seemingly unremarkable individual could commit a crime without leaving a trace, raising questions about human nature, guilt, and innocence.