The suspect who killed two French police posted a Facebook video from the scene of the murders calling for further strikes during the Euro 2016 championships, an expert on Islamist militancy said Tuesday.
David Thomson, a terrorism expert at Radio France Internationale, said the video was posted using the Facebook Live application at 8:52 pm (1852 GMT) on Monday.
It has since been removed.
In 13 minutes of footage shot at the home of his victims, Larossi Abballa announced that he had killed a policeman and his wife, said Thomson, author of a book on young French radicals.
"I don't know what to do with him," Abballa says in the footage, indicating the couple's three-year-old child sitting behind him on a couch.
The assailant, who was killed in a police raid around three hours later, also posted pictures of the dead couple on the account, which was in the name of Mohamed Ali.
During the assault, he attacked the 42-year-old police officer, stabbing him repeatedly outside his home, before going inside and slitting the throat of his 36-year-old partner, who also worked at a police station.
At the start of the recording, the 25-year-old convicted radical swears allegiance to Islamic State group leader Abu Bakr al-Baghdadi.
He then calls on other Muslims to attack "police, journalists, public figures, prison guards and rappers," listing around a dozen well-known figures by name.
"We will turn the Euro into a graveyard," he threatened, four days after the start of the football championships in a country on high alert after last November's jihadist carnage in Paris.
Abballa asked his 160 Facebook followers, particularly his IS group contacts, "to issue a statement claiming the attack".
The IS-linked Amaq news agency later announced that an "Islamic State fighter" had killed a policeman and his wife near Paris with a knife.