A man who stabbed four people to death at police headquarters in Paris adhered to a radical version of Islam, anti-terrorist prosecutors say.
Mickaël Harpon had contact with members of the Salafist movement, prosecutor Jean-Francois Ricard said.
He had exchanged text messages of a religious nature with his wife before Thursday's attack, the prosecutor said.
He also defended the deadly 2015 attack on the magazine Charlie Hebdo and other atrocities, Mr Ricard said.
Anti-terror investigators took over the inquiry on Friday. It was initially regarded as a criminal matter.
The 45-year-old IT expert, who worked at the police headquarters, was shot dead on Thursday by a junior police officer after he attacked colleagues in several offices at the central police building.
What do we know about the attacker?
Harpon had converted to Islam and had been in contact with the Salafist movement, Mr Ricard said, in reference to the ultra-conservative Islamic ideology.
The attacker "agreed with certain atrocities committed in the name of that religion", he said.
Among them was the Charlie Hebdo attack in 2015, when Islamist gunmen killed 11 people in the Paris office of the satirical magazine, before shooting dead a policeman outside.