The gruesome “selfie” taken by the man suspected of beheading his boss during an attack on a gas factory in France was sent to Syria, sources close to the investigation said Sunday.

Earlier Sources close to the investigation into Friday's attack near Lyon had revealed Yassin Salhi, a 35-year-old married father-of-three, sent a picture of himself with the severed head via the WhatsApp messaging service to a Canadian number.

“Though I can't comment on operational aspects of national security, I can say that we are helping French authorities in their investigation,” said Jean-Christophe de Le Rue, spokesman for Canadian public safety minister Steven Blaney.

The message was sent to a Canadian number, but investigators said they were still working to determine the final recipient, as the number used could be a relay to another phone in another location.

Authorities are now convinced that the final recipient is in Syria, where hundreds of people from France have gone to wage jihad.

Anti-terrorist authorities have identified 473 people who have left France to fight in Iraq or Syria and Prime Minister Manuel Valls said earlier Sunday that 1,800 people in France were “linked” in some way to the jihadist cause.

Authorities are questioning Salhi about Friday's attack, during which healso drove his van into a warehouse packed with dangerous gases in an apparent bid to blow up the factory and himself.

Canadian officials did not give details about how they are helping the French, but police powers allow them to trace calls or locate a phone by its number.

“A government's first duty is to ensure the safety of its citizens,” the spokesman said.

Canada has seen the radicalization of some of its youth, with about 100 people thought to have gone to Syria to join the Islamic State group.

Lawmakers recently endorsed a new anti-terror law that boosts powers of Canada's spy agency amid concerns of attacks within the country.