After the Islamic State (IS) extremist group claimed that a recent knife attack in central Paris was carried out by one of its "soldiers," Chechnya and France have exchanged angry barbs about who bears responsibility for the radicalization of the attacker, Khamzat Azimov.

The 20-year-old -- who was shot dead by Paris police on May 12 after stabbing five passersby, one fatally -- was born in the Chechen city of Argun in 1997, when the North Caucasus region of Russia was going through a brief respite between two wars that followed the collapse of the Soviet Union.

In 2002, when Azimov's parents fled with him to become refugees in France, he was just four years old.

Chechen leader Ramzan Kadyrov says this means that Azimov became radicalized as a result of his upbringing in France, and that France was solely to blame.

"In this light, I see fit to declare that all responsibility for the fact that Azimov has embarked on the criminal path rests with the French authorities," Kadyrov said in a Telegram message on May 13. "He was only born in Chechnya, but he grew up in French society, and his individuality, views, and convictions were formed there."

But French Foreign Minister Jean-Yves Le Drian responded angrily to Kadyrov's claim, suggesting that extrajudicial crackdowns against Chechen civilians by Kadyrov's security forces contributed to Azimov's radicalization as he grew up within France's Chechen refugee community.

"We have no lessons to learn from a dictator who refuses even the beginning of any rule of law in his own country, and who knows perfectly well that thousands of Chechens are fighting alongside [IS extremists]," Le Drian said on May 14.

Investigations In France And Chechnya

Since the attack, authorities in both France and Chechnya have been investigating Azimov's background and connections to determine whether he had accomplices or acted alone in Paris when he stabbed to death a 29-year-old man and injured four other people.

Kadyrov's security forces deployed armored personnel carriers in Argun to round up members of Azimov's family for questioning.

In France, prosecutors on May 15 continued to hold Azimov's parents in custody to question them about whether he received help planning his stabbing spree.

Meanwhile, France's DGSI intelligence agency was questioning Azimov's closest high-school friend, a 20-year-old of Chechen descent who was detained at his home in Strasbourg by masked police a day after the Paris knife attack.

In Argun, Azimov's relatives refused to talk to RFE/RL on the record, saying they were afraid to be identified in media reports during the ongoing investigation by Kadyrov's security forces.

But privately, some relatives spoke to RFE/RL about his life before his family fled from Chechnya.

Born Between Wars

Azimov was two years old in 1999 when Chechnya's second war began, sending at least 200,000 civilians fleeing to neighboring Russian republics during the first month of the conflict.

The International Helsinki Federation for Human Rights says it was a time when Russian security services and their Chechen allies were building up a network of clandestine prisons to detain and torture civilians in order to obtain information about rebel fighters.

By 2002, when Azimov's family fled Chechnya, the Argun region was particularly notorious for forced disappearances and the torture of civilians at the hands of government troops.

More than 500 residents of Argun staged a mass demonstration in the town in January 2002 against sweeping Russian military operations that detained civilians in order to hunt down Chechen rebel fighters.

The Russian human rights group Memorial highlighted one infamous case in Argun that it described as the "unlawful arrest and extrajudicial killing" of 28-year-old Shamil Idrisov.

But Chechnya's prime minister at the time, Stanislav Ilyasov, rejected the demands of protesters and rights groups, saying it was essential for troops to continue special operations to identify and capture rebel fighters.

Child Refugee

Relatives of Azimov told RFE/RL those crackdowns in Argun by Russian and Chechen security forces were the reason his parents fled with the family to France in 2002.

Azimov's parents settled the family in the town of Nice in southern France upon their arrival that year.

Relatives said it took two years for the family to be granted the status of political refugees, which allowed them to look for work and settle in France.

Azimov became a naturalized citizen of France in 2010, shortly after his mother received French citizenship.

Best Friend In Strasbourg

In 2014, when Azimov was a teenager, he and his family moved to Strasbourg in eastern France where there is a large Chechen refugee community.

Azimov attended Marie Curie High School in Strasbourg where he befriended fellow student Abdul Hakim.

Other former classmates said the two were "best friends" and were always together, both in and outside of school, during their final year of high school.

They described Azimov as religious and "very discreet," saying he was calm, kept to himself, and celebrated the Muslim holy month of Ramadan -- but also enjoyed sports and playing video games.

Others in Strasbourg who knew Azimov told RFE/RL that he sporadically attended a Chechen-run mosque in the city but usually prayed "privately" at a friend's home.

One former student at Azimov's high school, who declined to be identified by name, said Azimov had expressed interest in going to Syria.

France's AFP news agency quoted a French investigator who said Azimov had been questioned by antiterrorism police in 2017 "because he knew a man who was in contact with a person who had gone to Syria" to fight alongside IS militants.

Other French media reports suggest Hakim may have been a link between Azimov and IS extremists in Syria.

In 2016, French police listed both Azimov and Hakim on a database of people thought to have a "propensity for radical actions."

Hakim had been placed under surveillance after marrying Ines Hamza, a woman from Paris who allegedly tried to travel to Syria in January 2017 to join IS militants.

When French authorities transferred Hakim from Strasbourg to Paris on May 14, escorting him handcuffed and with his face covered, he was wearing a T-shirt that said "Defend Grozny" and that depicted an assault rifle.

One-Room Paris Apartment

Azimov moved to Paris with his parents in 2016, taking up residency in a single-room apartment on the north side of the French capital in a building that houses other refugees.

As a part-time house painter, relatives told RFE/RL that Azimov's father had difficulty earning enough money to live in a costlier residence while Azimov was studying to work in the medical field.

Neighbors described the family as discreet and said they didn't engage in overt displays of their Muslim faith.

In the aftermath of Azimov's May 12 stabbing spree, the online IS propaganda agency Amaq posted a video online and claimed it was Azimov pledging allegiance to IS.

The video featured a young man wearing a hood with only his eyes showing and the lower part of his face covered by a black cloth. The man in the video spoke in French but did not identify himself by name.

It was not immediately possible to confirm the IS claim that person in the video was Azimov.

Written by Ron Synovitz with reporting by RFE/RL's North Caucasus Service in Paris, Strasbourg, and Chechnya.