The Taoiseach has said that the garda review of the investigation into the murder of Sophie Toscan du Plantier will be done objectively and professionally.
Micheál Martin said he did not believe the review was "optics" and that with advances in DNA and forensics, opportunities arise in criminal cases over time.
He also said it was important that "no stone be left unturned" to bring the perpetrator to justice.
Ms Toscan du Plantier was found dead on a laneway leading to her holiday home in Schull on 23 December 1996.
Ms du Plantier's son last week described the announcement as "very good news for justice".
Speaking on RTÉ's News At One programme, Pierre-Louis Baudey-Vignaud also said his family has "big expectations" from it after waiting over 26 years.
"My family are all deeply involved in the fight for justice of my mother," he said.
"I think this new investigation is, in a way, the gardaí recognising there have been some mistakes during the original investigation, and so they need to do a new one," he added.
Gardaí continue to appeal to anyone with information to contact the investigation team at Bantry Garda Station or the garda confidential line 1800 666 111.