Two men went on trial on Tuesday over the 2018 murder of an elderly Jewish woman that provoked protests and alarm in France about anti-Semitic crime.
President Emmanuel Macron attended the funeral of the Holocaust survivor who escaped a notorious 1942 roundup of more than 13,000 Jews in Paris by fleeing with her mother to Portugal when she was nine years old.
Two men have been charged with her killing, a 25-year-old homeless man with psychiatric problems and the 31-year-old son of one of Kroll's neighbors.
Mrs Knoll's son expects 'tough verdict'00:59
The pair, who met in prison and have past convictions for theft and violence, both deny killing the frail and immobile grandmother and each blames the other for her death.
"We will need a miracle for the truth to come out of their mouths," Gilles-William Goldnadel, a lawyer acting for Knoll's family, told reporters as he entered the court, adding that it was a case of "anti-Semitism motivated by financial gain."
Prosecutors are treating the murder as an anti-Semitic hate crime because one of the men said he had overheard the other "talking about Jews' money and their wealth" and that he shouted "Allahu Akbar" ("God is greatest") while stabbing her.
The investigation had also shown one of the suspects, named as Yacine Mihoub, had an "ambivalent" attitude towards Islamic extremism, prosecutors claim.
"They're monsters," Knoll's son, Daniel Knoll, told reporters on Tuesday. "We are expecting a very severe verdict."
Both Mihoub, 31, and co-accused Alex Carrimbacus, 25, were present in court or the trial which is due to last until November 10.
'Murdered because Jewish'
The murder was the latest in a series of attacks that have horrified France's 500,000-strong Jewish community and exacerbated concern about how rising Islamic extremism is fueing anti-Semitism.
An estimated 30,000 people took part in a silent march in her memory in March 2018 that was attended by government ministers and the heads of France's political parties.
One of the organizers, Sabrina Moise, said at that the time that while she "loves France" she felt it was "no longer safe for Jews because of galloping anti-Semitism."
In 2012, Islamist gunman Mohamed Merah shot dead three children and a teacher at a Jewish school in the southwestern city of Toulouse.
Three years later, a gunman killed four people in a hostage-taking at a Jewish supermarket in the French capital.
And in 2017, an Orthodox Jewish woman in her sixties, Sarah Halimi, was thrown out of the window of her Paris flat by a neighbor shouting "Allahu Akhbar".
France's highest court ruled in April that the killer, Kobili Traore, was not criminally responsible for crime after succumbing to a "delirious fit" under the influence of drugs and could not go on trial.
That ruling infuriated the victim's family as well as Jewish groups, and prompted Macron to urge a change in French law to ensure people face responsibility for violent crimes while under the influence of drugs.
It also prompted protests in France and also Israel.
Speaking about Knoll, Macron had said her killer "murdered an innocent and vulnerable woman because she was Jewish and in doing so had sullied our most sacred values and our memory."