A French prosecutor says Friday's attack on a U.S. gas factory in Lyon bears the hallmarks of the Islamic State militant group.
Prosecutor Francois Molins said Tuesday that the man who is suspected of carrying out the attack, Yassin Salhi, had a "terrorist motive" when he beheaded his employer and attacked the gas factory.
"Salhi decapitated his victim, he hung the head on a fence to get maximum publicity, as he told us during interrogation," said Molins.
Salhi, who was arrested soon after the attack, is being held on suspicion of terrorism.
He is suspected of crashing his vehicle onto the factory grounds and causing an explosion Friday.
After Friday's attack, French President Francois Hollande raised the security level in the region of Rhone-Alpes to the highest possible level.
Hollande announced the move after a high-level security meeting Friday afternoon, several hours after the attack on the factory in the small town of Saint-Quentin-Fallavier, southeast of Lyon.
French counterterrorist forces were deployed to the gas factory, where a body and decapitated head was found covered with Arabic writing. A flag with Islamist inscriptions was also found nearby.
Security has been heightened in France since January attacks at the Paris headquarters of a satirical magazine and at a kosher supermarket, bookending a three-day siege of violence that left 20 people dead.