Several thousand people took part in a silent march in Paris on Wednesday in memory of an 85-year-old Jewish woman, killed in a grisly attack believed to be anti-Semitic.
The leaders of several political parties joined the march for Mireille Knoll, whose partly burned body was found in her Paris home at the weekend.
Knoll, who escaped the mass deportation of Jews from France during World War II by fleeing abroad, was stabbed 11 times in an attack that the perpetrators apparently tried to conceal by setting fire to the apartment.
She was found dead by firefighters.
A neighbour in his twenties and a homeless youth have been charged over the latest in a series of attacks that have horrified France's 500,000-strong Jewish community, Europe's largest.
President Emmanuel Macron attended her funeral earlier Wednesday.
Community leaders carrying white roses and lawmakers wearing their official sashes led the march from Place de la Nation to Kroll's apartment building in the east of Paris.
Interior Minister Gerard Collomb and Culture Minister Francoise Nyssen were part of a large government contingent.
Le Pen, who had been told she was not welcome by the president of the CRIF umbrella group of French Jewish organisations, which organised the march, was booed on arrival with a group of party members.
Far-left leader Jean-Luc Melenchon was also heckled after he also defied a call to stay away.
The two politicians both left shortly afterwards.
"I made it very clear, I explained that the high number of anti-Semites on both the extreme left and the extreme right made these parties unacceptable," CRIF leader Francis Kalifat told RTL radio earlier.
Investigators are working on the theory that the frail Knoll was targeted because she was a Jew.
The accused neighbour had served time in prison for sexually assaulting a 12-year-old girl.
Sources close to the inquiry said he and his accomplice had given conflicting accounts under questioning, each accusing the other of carrying out the attack.
"What the Nazis were unable to do, criminals, thugs have done with the same hatred," Haim Korsia, the chief rabbi of Paris, told AFP.
The killing comes a year after an Orthodox Jewish woman in her sixties was thrown out of the window of her Paris flat by a neighbour shouting "Allahu Akhbar".
A judge confirmed just last month that the April 2017 murder of Sarah Halimi was motivated by anti-Semitism, a delay that drew the ire of several Jewish groups.
Halimi's murder reignited the debate over anti-Semitism in working-class districts in France which has been used to recruit jihadists.
In 2012, an Islamist gunman shot dead three children and a teacher at a Jewish school in the southwestern city of Toulouse.
Three years later, an associate of the two brothers who massacred a group of cartoonists at satirical newspaper Charlie Hebdo killed four people in a hostage-taking at a Jewish supermarket in Paris.
Officials at Paris's main mosque said Knoll's killing was "denounced and condemned by all the Muslims of France".