A 23-year-old man has been admitted to a psychiatric hospital after police discovered he had kept the corpse of his dead mother in the cellar for a year. 

Authorities said the 61-year-old mother from the village of Blain, near Nantes, appears to have died a natural death in February 2011. Autopsy results are expected on Friday but a first examination of body did not find any wounds or traces of violence.

"It’s a human tragedy, but the investigation so far hasn’t uncovered a criminal motive," a source close to the investigation told Le Parisien. The same source said tests show the son does not suffer from a serious psychiatric illness but was severely affected by the death of his mother.  

Speaking to the police, the son says his mother was overweigh and suffered from high blood pressure, and that she stopped taking care of herself in the period leading up to her death last year.

The young man put the body of his mother on a bed in the cellar and did not change his routine. He continued to shop for household groceries and paid the bills. 

His mother was a recluse and it appears the neighbours did not notice she had died.

It’s only when prosecutors opened an investigation into her disappearance and summoned the son for questioning, that he led them to her body. 

On Wednesday, the son was briefly detained by the police before being released and admitted into hospital.