An investigation into a security breach at the Paris police headquarters has been launched following the deaths of four officers.
A long-serving police employee stabbed four colleagues to death on Thursday (October 3) at the Prefecture de Police Paris, close to Notre-Dame, before he was shot and killed.
France's interior minister has acknowledged that there was a breach in security that failed to detect signs of radicalisation in the employee who carried out the attack.
Christophe Castaner told France Inter radio the attacker had previously "justified" the deadly 2015 Islamic extremist attack on satirical newspaper Charlie Hebdo in front of his colleagues - but no written report was made at the time.
An internal investigation has now been launched, in addition to the judicial investigation.
The counter-terrorism prosecutor said the attacker was probably in contact with members of an ultra-conservative Islamic movement.
His wife was released from police custody on Sunday without any charges, Mr Castaner said.
