The suspect was born in Moscow.
The French police have arrested nine people after a suspect beheaded a school teacher in broad daylight on the street in a Paris suburb on Friday, police sources said.
Prosecutors said the attacker, shot dead by police soon after, wanted to punish the teacher for showing his pupils cartoons of the Prophet Mohammad in a civics class on freedom of expression earlier this month.
A suspect shot dead by police after the beheading of a history teacher near Paris was an 18-year-old Chechen, French police said.
The attack has upset moderate French Muslims, and a group of imams in the Lyon region were holding a special meeting on Sunday to discuss what the group called "the appalling assassination of our compatriot by a terrorist who in the name of an uncertain faith committed the irreparable".
The government has portrayed the killing as an attack on the heart of French values.
In Conflans-Sainte-Honorine, about 30 kilometers from Paris, bouquets of flowers were stacked in front of Paty's shuttered school.
Visibly moved, the president said that "the entire nation" stood ready to defend teachers and that "obscurantism will not win".
Four people, including a minor, have also been arrested. All were related to the assailant, the source added.
Demonstrations are being held in dozens of cities across France in a show of solidarity and defiance after the decapitation of a teacher outside his school on Friday for showing pupils cartoons of the Prophet Mohammed in a lesson on freedom of speech.
Witnesses said he was spotted at the school on Friday afternoon asking pupils where he could find Paty.
"According to my son, he was super nice, super friendly, super kind", said the parent, Nordine Chaouadi.
According to his school, Paty had given Muslim children the option to leave the classroom before he showed the cartoons, saying he did not want their feelings hurt.
A French teacher marches on the streets of Paris
There had been no previous indication that he was a potential radical, a source close to the investigation said. The teacher had discussed caricatures of Islam's Prophet Muhammad with his class, authorities said.
One who had been to school with him said he had become noticeably religious in recent years.
"I am a parent of a student at this college".
Darmanin also plans to bring into focus the question of the right to asylum, since an 18-year-old Chechen refugee, identified only as Abdoulakh A., is suspected of killing Paty.
Police were called to the area after receiving reports of a suspicious person loitering near the victim's school. They opened fire and he later died of his injuries. No explosives were found on his body after it was checked by a bomb disposal unit.
Reprising the "I am Charlie" slogan following the January 2015 attacks, Castex added, "I am more than ever Charlie".
Some waved French flags and brandished banners celebrating free expression, as speakers paid a somber tribute to the country's latest victim of terrorism.
It also comes just days after a follower of the Islamic State group who attacked a police officer with a hammer outside the Notre-Dame cathedral in Paris was sentenced to 28 years in jail.
Less than a month ago, a man originally from Pakistan used a meat cleaver to attack and wound two people who were on a cigarette break outside the offices where Charlie Hebdo was based at the time of the 2015 attack.
Seventeen people were killed in the three-day spree that heralded a wave of Islamist violence in France that has so far claimed more than 250 lives.
Charlie Hebdo responded to Friday's attack on its Twitter account, writing: "Intolerance has crossed a new threshold and does not seem to give ground to anything in imposing its terror on our country".