PARIS (AP) — French authorities have filed preliminary kidnapping charges against relatives of a 4-year-old boy whose 1984 murder has been one of the country's longest-running mysteries.

Dijon Prosecutor Jean-Jacques Bosc said Friday that a great-aunt and great-uncle of Gregory Villemin are accused of kidnapping and illegal confinement followed by death.

The suspects, Marcel and Jacqueline Jacob, deny any involvement. Their lawyers assailed prosecutors for what they called an unjustified, premature move.

The prosecutor said new evidence shows a link between the kidnapping and anonymous letters and phone calls around the killing. Handwriting analysis on one letter led investigators to the great-aunt.

But the prosecutor acknowledged that he still doesn't know who killed the boy 32 years ago. His body was found in a freezing Burgundy river, bound hand and foot.