Christophe Castaner told France Inter radio Monday 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 been launched, in addition to the judicial investigation. The longtime police employee stabbed four colleagues to death Thursday before he was shot and killed. The counterterrorism prosecutor said the attacker was likely in contact with members of an ultra-conservative Islamic movement.
His wife was released from police custody Sunday without any charges, Castaner said.