Ian Bailey is being tried in absentia after Ireland refused to extradite the 62-year-old former journalist over the killing of Sophie Toscan du Plantier, the wife of a prominent French film producer.
"I can only regret that the defendant is not here today," said the son of the victim, Pierre-Louis Baudey-Vignaud, in court on the third day of the trial.
"The cruel failure to come and explain the contradictions that were evoked over the last three days shows a very great lack of courage," said Baudey-Vignaud, 38.
Baudey-Vignaud, who named his daughter Sophie in tribute, praised his mother, who died aged 39 when he was 15, as a "women full of love".
'I believed my son'
Several witnesses who gave evidence at his trial in Paris on Tuesday said Bailey indicated he had committed the crime afterwards.
The first witness, Amanda Reed, told the court that Bailey had confessed to her son a few months after Sophie Toscan du Plantier was beaten to death at her holiday home in County Cork in southwest Ireland.
Reed's son, who was 14 at the time, gave a statement to the Irish police afterwards, but declined an invitation to testify at the French trial because he remains traumatised by the case.
"He was terrified. I believed my son and I have never questioned what he said," Reed, 60, told the court, according to a French translation of her remarks in the witness box.
Bailey, who was twice arrested by Irish police but never charged, denies killing Toscan du Plantier, the wife of Daniel Toscan du Plantier, the former director-general of the Gaumont Film Company and who died in 2003.
He was found with scratches afterwards which he attributed to a Christmas tree and cutting up a turkey for dinner.
A lawyer for Bailey, who now sells pizzas in the Irish village of Schull where the murder occurred, has called the French trial a "judicial error".
An undated picture taken in the French southern village of Combret, shows Sophie Toscan du Plantier, a French woman who was murdered in Ireland in 1996. Photo: AFP
A second witness, Bill Fuller, a cook and former friend of Bailey, told the court on Tuesday that the suspect had confessed to him in an odd conversation during which he referred to himself in the second person.
"It's you who killed her," Fuller remembered Bailey saying, adding that Bailey had been sexually attracted to Toscan du Plantier and often talked about himself in the second person.