Lyon, France/Bari, Italy -- Three weeks after the brutal, livestreamed killing of 45-year-old Assyrian Christian Ashur Sarnaya in Lyon, French investigators have made a key breakthrough. A 28-year-old Algerian man, suspected of being present at the scene of the attack, was arrested Thursday in southern Italy under a European arrest warrant, according to the Lyon public prosecutor, Thierry Dran.

The suspect was detained in Andria, near Bari, in the Apulia region. He has been presented to Italian judicial authorities, who will decide in the coming weeks whether to transfer him to France. His eventual hearing by French investigators is expected to shed light on the circumstances surrounding Sarnaya's death, which remains shrouded in uncertainty.

Sarnaya, a wheelchair user originally from Ankawa in Iraq's Kurdistan Region and living in Lyon since 2014, was stabbed in the neck by three hooded attackers who fled the scene. Witnesses reported seeing a masked man in black shortly afterward.

Sarnaya was known for sharing his Catholic faith online, and his death has drawn condemnation in France and abroad. While the crime has provoked outrage among Christian and religious freedom advocates, investigators have not classified it as religiously or terrorist-motivated, and national anti-terrorism authorities have not taken over the case.

The Lyon public prosecutor's office has opened a judicial investigation for premeditated murder but has not ruled out any hypothesis. "At this stage, we do not favor any thesis, nothing directs us toward a solid path, whether criminal, political, religious, or linked to narcotics," a police source told AFP. The national anti-terrorism prosecutor's office has been in contact with Lyon investigators but has not taken over the case.

Detectives from the national police's central office have provided technical support to analyze digital evidence. Preliminary findings suggest that the killer was waiting for Sarnaya outside his building and fled on foot immediately after the attack. A witness filmed a figure dressed in dark clothing and wearing a hood leaving the scene. Rumors of a man in black circulated widely in the neighborhood the following day.

Investigators are also examining possible online threats. In several of his TikTok videos, Sarnaya complained about his content being repeatedly reported by Muslim users, leading to its removal. His sister, Madelin, told reporters that he had received a threatening message showing a photo of the two of them outside their building. "As a warning?" she asked, still struggling to comprehend the killing.