Chilean Nicolas Zepeda was charged with murder shortly after being extradited to France over the 2016 disappearance of his Japanese ex-girlfriend, prosecutors said on Friday.
Zepeda, 29, is the only suspect in the disappearance and alleged murder of Narumi Kurosaki, whose body has not been found, in a case that has gripped Japan and France.
Kurosaki, then 21, vanished from her university in Besancon, near the French Alps, in December 2016 after having dinner with Zepeda.
By the time her disappearance was reported days later, Zepeda had returned to Chile.
France has been fighting for more than three years to have him extradited, and local prosecutor Etienne Manteaux confirmed he had been charged shortly after touching down in France.
A judge later ordered him to be detained.
French investigators believe Zepeda killed his ex in a jealous rage.
He had been under house arrest in the Chilean seaside resort of Vina del Mar, 120 kilometres (75 miles) west of Santiago.
The handover was delayed and complicated by the coronavirus pandemic and subsequent border closures.
Narumi should have celebrated her 25th birthday on Thursday, Sylvie Galley, lawyer for Kurosaki's family said, but the day had instead been one of "mourning".
Her mother and father "beg Nicolas Zepeda to reveal the whereabouts of Narumi", she added, "because Narumi's place is near her parents".
- 'We will never forgive' -
Zepeda's extradition marks the third Chilean suspect sent to France, even though French authorities refuse to send former Chilean guerrilla Ricardo Palma Salamanca back to his homeland to stand trial for the 1991 murder of right-wing senator Jaime Guzman.
"Three years have passed since my beloved daughter disappeared... I pray that Nicolas will be tried in France, I would give my life for this," Kurosaki's mother Taeko wrote in a letter presented to the court in Chile.
"We will never forgive Nicolas, who took Narumi's life and her from the whole family."
According to investigators, Zepeda, the son of a wealthy Chilean family, met Kurosaki in Japan in 2014.
After a breakup, he went to Besancon at the beginning of December 2016 to see her again, and on the evening of December 4 the pair entered her residence together.
French prosecutors say several students heard "howls of terror" that night, but nobody called the police.
At the time of her disappearance, Kurosaki was in a new relationship, which prosecutors said angered Zepeda, who allegedly threatened her in an online video he later removed.
Investigators allege that after arriving in France in 2016, Zepeda hired a car and drove to Besancon, stopping on the way to buy matches, flammable liquid and bleach at a supermarket.
Zepeda, who was questioned in April last year by a Chilean judge in the presence of French investigators, has denied involvement in Kurosaki's disappearance.
Chilean Nicolas Zepeda, centre, being escorted by police at Santiago international aiport ahead of his flight to Paris
Prosecutors believe Nicolas Zepeda, seen here in Santiago in March of 2020, killed his ex-girlfriend Narumi Kurosaki in the French city of Besancon in a jealous rage in 2016