The main suspect in an assault that left one tourist dead and two other people injured in Paris was known to French intelligence services for Islamist extremism and had pledged allegiance to the Islamic State before the attack, the French authorities said on Sunday.
Jean-François Ricard, France’s top antiterrorism prosecutor, said at a news conference in Paris that the suspect had shown “persistent radicalization,” had a prior terrorism conviction and had been in contact online with jihadists responsible for terrorist attacks in France.
But the suspect, identified as Armand Rajabpour-Miyandoab, also suffers from psychiatric disorders, and the authorities had not detected any imminent plans to carry out an attack, despite a recent alert raised by the suspect’s mother, Mr. Ricard said.
The attack on Saturday laid bare not only the difficulty in monitoring suspected extremists with mental health issues but also the challenges that lie ahead for President Emmanuel Macron’s government as it tries to reassure the world that the 2024 Summer Olympic Games in Paris will be safe.
In a sign of how seriously the authorities were treating the episode, Prime Minister Élisabeth Borne oversaw a special cabinet meeting on Sunday “to provide a full update on the security arrangements in place, the treatment of the most dangerous individuals and the aftermath of this fatal attack,” her office said.
The French interior minister, Gérald Darmanin, told TF1 television on Sunday that the country was “durably under threat from Islamist terrorism” but said it would be ready to host the Olympic Games. They include an opening ceremony on the Seine that critics have called extremely difficult to secure.
Mr. Macron’s government says that tens of thousands of security forces will be deployed during the event, and Mr. Darmanin said that areas near the opening ceremony would be largely cordoned off, with tight security and highly restricted access “so that this kind of thing does not occur.”
France was hit with large-scale Islamist terrorist attacks in 2015 and 2016, and then by a string of smaller but deadly shootings and stabbings in subsequent years. The country has been on its highest terrorism threat alert since October, when a teacher was killed in northern France.
The French government says that the police and intelligence services have thwarted over 40 attack plots since 2017 but that the terrorist threat is particularly acute at the moment because of the war between Hamas and Israel.
The man who was killed in Saturday’s attack, a 23-year-old German tourist of Filipino origin, was struck twice with a hammer and four times with a knife near the Eiffel Tower by Mr. Rajabpour-Miyandoab, said Mr. Ricard, the prosecutor.
As the police were pursuing him, the suspect slightly wounded two other people, a Frenchman and a British citizen, with the hammer, Mr. Ricard said. Confronted by the police, he claimed he had an explosive belt. That turned out not to be the case; he was arrested after an officer subdued him with a stun gun, the authorities said.
In a video recorded before the attack, Mr. Rajabpour-Miyandoab, speaking in Arabic, pledged allegiance to the Islamic State, used a name to introduce himself that referred to the Islamic State in Afghanistan and expressed support for jihadists around the world, Mr. Ricard said. The video was published on X, formerly Twitter, from an account that was opened last month and that featured numerous posts referring to Hamas and the war in Gaza, the prosecutor said.
Mr. Rajabpour-Miyandoab and three family members and associates are still in police custody for questioning, Mr. Ricard said.
Mr. Rajabpour-Miyandoab was born in 1997 to a nonreligious family, but he converted to Islam in 2015 and “very quickly embraced jihadist ideology,” Mr. Ricard said. In 2018, he was convicted on charges of being part of a criminal conspiracy to prepare a terrorist attack that was not carried out.
At the time, Mr. Ricard said, investigators determined that Mr. Rajabpour-Miyandoab had “massively consulted” propaganda videos and documents spread online by the Islamic State, and that in 2016 he had expressed the desire to join the group in Syria or Iraq. Investigators also found that Mr. Rajabpour-Miyandoab had connected online with other Islamist extremists, including some who later became notorious for attacks of their own.
Mr. Rajabpour-Miyandoab became friends on Facebook with the man who later murdered an off-duty police officer and his partner at their home near Paris, Mr. Ricard said, although the two men did not exchange any messages. Mr. Rajabpour-Miyandoab also chatted online with one of the assailants in the attack that killed a priest in his church in Normandy, Mr. Ricard said. After his release from prison in 2020, Mr. Rajabpour-Miyandoab was also in touch with the man who later murdered Samuel Paty, a French history teacher.
His release from prison came under strict conditions, Mr. Ricard said, including an order to undergo psychiatric treatment. He also said that treatment stopped in April 2023, although intelligence services continued to monitor Mr. Rajabpour-Miyandoab.
Mr. Darmanin, the interior minister, told TF1 on Sunday that Mr. Rajabpour-Miyandoab’s treatment had stopped at the request of “certain doctors,” but did not elaborate. He argued that security services should be able to overrule doctors in certain cases to force suspected extremists with psychiatric disorders — “there are many of them,” he said — to undergo treatment.
In October, Mr. Rajabpour-Miyandoab’s mother expressed worries that her son was growing increasingly reclusive, but the security services had no grounds to bring charges against him, Mr. Ricard said.
“These are the individuals who are always the hardest to track,” Laurent Nuñez, the head of the Paris police, told BFMTV on Sunday. “Because you have a background of radicalization, and you have these psychiatric disorders that muddy the waters and make it harder for intelligence services to analyze.”