An examination of the attacker's phone, which killed four people in the Paris Police Headquarters on Thursday, seems to betray a premeditated act, and also revealed a closeness with members of the Salafist movement.

Forty-eight hours after the bloody attack that plunged the Paris Police Prefecture, killing five people, including the assailant, the investigation took a terrorist turn. Since Friday night, the National Prosecutor's Office has taken over the case because the police have collected new elements that suggest an attack on the background of Islamist radicalization, while the wife of the knife killer is still in custody.

By Thursday evening, the criminal brigade had stressed the extreme violence of the operating mode and its similarities, for some victims, with the videos of the group Islamic State. But this rapprochement still seemed insufficient to attest to the radicalization of the killer. Behind the scenes, the decision to focus on the attack was the subject of a serious standoff. It was taken after long and heated discussions between the investigators and magistrates, between the Paris Public Prosecutor's Office and the National Anti-Terrorist Office, between the Ministry of the Interior and the Prefecture of Police.

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SMS exchanges before the acting out

It is the work of the investigators that has brought to the forefront the trail of a terrorist act. This assumption was suddenly substantiated when the police began to examine the contents of the killer's cell phone. His last exchanges of text messages are unequivocal: the day of the drama, shortly before taking action, he had indeed announced to his wife that he had just bought a ceramic kitchen knife. A blade of 33 centimeters, with which he was preparing to commit the killing. In response, his wife would not have dissuaded him from acting.

How long had she known that her husband was going to commit an attack? Is she complicit? These are all questions that investigators have been asking him since Thursday. On Friday, his detention was extended. Her statements reinforce the thesis of an Islamist drift of her husband, converted for 18 months. Thanks to the telephone, the investigators also discovered that this administrative agent authorized defense secret, and charged since 15 years of the computer maintenance of the direction of the intelligence of Paris, was sometimes in contact with individuals belonging to the Salafist movement.

Described as a reserved man, taciturn, this employee had made statements deemed inappropriate in 2015, after the attacks of Charlie Hebdo , to the point of being called to order by his superiors.