The man who beheaded his boss and tried to blow up a U.S.-owned gas factory in Lyon last week had a "terrorist motive" and links to the Islamic State (ISIS) group in Syria, a French prosecutor confirmed Tuesday.
The investigation "indicates a terrorist motive in Yassin Salhi's act, even though it is justified by personal considerations," said Paris chief prosecutor Francois Molins.
Salhi took two photos of the macabre beheading scene and sent them almost immediately to a friend in Syria, and the friend had requested permission from ISIS militants to distribute the snapshots, Molins said.
Salhi, 35, a truck driver with a history of radical Islamic ties dating back to 2003, was arrested Friday shortly after he rammed his gas-filled delivery van into a warehouse at the Air Products factory that contained dangerous chemicals, causing an explosion.
Firefighters alerted by the blast found him trying to open gas bottles inside the factory, shouting "Allahu Akbar" (God is greatest), before making the grisly discovery of the severed head of Salhi's 54-year-old boss, Herve Cornara.
According to Molins, Salhi has denied he was motivated by terrorism and said he neither remembers the beheading nor sending photos.
"According to him his motive was only personal and not terrorist. One does not exclude the other," Molins said. "He decapitated his victim, he hung the head on a chain, and he wanted to get the maximum publicity possible."
Molins has requested preliminary terrorism charges to be filed against Salhi and has opened a formal terrorism investigation, including into his ties with the French jihadist in Syria, identified as Sebastien Younes.
The prosecutor said that Salhi claimed to have strangled his boss "with one hand" before stopping 500 meters before the factory to decapitate him with a knife with a 25-centimeter blade.
The severed head was surrounded by two Islamic flags which Salhi said he had bought the night before the attack.
"This corresponds very precisely to the orders of Daesh (ISIS) which calls regularly for acts of terrorism on French soil and in particular to cut the throats of unbelievers.
"The decapitation recalls the habitual modus operandi of this terrorist organization," said Molins.
Salhi, who refused to talk for his first 24 hours in custody, later claimed he was suffering from amnesia and had no memory of the macabre staging of the severed head.
The suspect claimed his motives were "purely personal and his act was not terrorist," said Molins, adding that Salhi had blamed a fight with his employer as well as a dispute with his wife for pushing him to commit the crime.
But Salhi was in "regular contact" with Younes, 30, known to have left France for Syria last November.
The Friday attack came days after ISIS militants urged followers to strike during the Muslim holy month of Ramadan.
During a raid on those close to Younes, who is from Besancon in eastern France, police uncovered a telephone in which he said in a WhatsApp conversation on the day of the attack that he indeed knew Salhi and was "one of the reasons he did that," referring to the crime.
Molins said Salhi had spent a year in Syria in 2009 with his wife and children, claiming he was there to learn Arabic.
Information from The Associated Press and AFP were used in this report.