At least one person has information about the murder of Sophie Toscan du Plantier and has not come forward yet, gardaí have said.
Investigators have renewed their appeal for witnesses almost 26 years since Ms Toscan du Plantier was killed.
The French film-maker was found dead in Schull in west Cork on December 23rd, 1996.
Former journalist Ian Bailey was twice arrested in connection with her death, but has never been charged in Ireland.
Superintendent Joe Moore of Bantry Garda Station said new witnesses in the case had been identified on an "almost weekly basis" in Ireland, France and Britain.
He said gardaí want to speak to any person who met, spoke with or had any interaction with Ms du Plantier from when she arrived in Ireland on December 20th, 1996, to when her body was discovered outside her holiday home near Schull on December 23rd.
“Any person who has knowledge of the period of time must come to An Garda Síochána and let us know exactly what happened at the home and grounds where Sophie lived during those hours on those dates," he said.
“I want to speak with any person who was in the Toormore area of Co Cork between December 20th and December 23rd, 1996, in particular anyone who was driving on the R591 or R592.
"You have to put yourself in the shoes of Sophie’s family. Her grandchildren have never seen their grandmother, her son has been without his mother since he was 15 years of age, it’s time that they came forward and it’s time that they gave us that information and I can guarantee that they will be treated confidentially.”
Supt Moore would not be drawn on whether Mr Bailey, who was found guilty in absentia of Ms du Plantier’s murder by a French court, is a suspect or person of interest. Mr Bailey has always denied any involvement in Ms du Plantier’s death.
He said the people of the Mizen Peninsula have been “fantastic” in supporting the ongoing investigation into the killing.
“They keep coming forward with information and that’s why I believe there is further information out there. There was never a crime of this sort in this area for over 100 years and there hasn’t been since and An Garda Síochána want to solve it," he said.
“I would urge persons with information in relation to the murder of Sophie Toscan du Plantier to please come forward either to the investigation team at Bantry Garda Station at 027 20860, your local garda station or the Garda Confidential line on 1800 666 111."