The family of Sophie Toscan du Plantier hope the exhumation of her body this week will lead to new DNA clues about her killer.
A French judge, Patrick Gachon, has ordered that the body of Ms Toscan du Plantier be exhumed tomorrow in Mauvezin in south-west France, and a new post mortem undertaken.
The wife of the late Daniel Toscan du Plantier, former chief of France's Gaumont film studios, Ms Toscan du Plantier was found beaten to death on 23 December 1996 in Schull, Co Cork. She was 39.
No one has ever been charged with her murder.
A lawyer for the family, Eric Dupond-Moretti, said the investigation which was opened in France in 1997 at the behest of the family would have to start from scratch again.
Jean-Pierre Gazeau, brother of Ms Toscan du Plantier's mother, Marguerite Bouniol, said the family hoped new DNA evidence - which could lead to the capture of her killer - would be found on her remains.
Mr Gazeau is president of the Association for the Truth about the Murder of Sophie Toscan du Plantier, which the family established last year to help in the hunt for the killer.
Gardaí made only a brief comment on the exhumation, saying their investigation was still ongoing, but referring any enquiries to the French authorities.
Ms Toscan du Plantier's body, in nightclothes and wearing boots, was discovered by a neighbour on a lane leading to her holiday home in Schull.
A preliminary inquest was told she had suffered severe head and facial injuries which had been caused by a blunt instrument. No murder weapon was ever found.
