Prosecutor François Molins said Saturday that the 40-year-old Algerian appeared to have become radicalised through the internet and Islamic State (IS) armed group propaganda.
"Farid I confessed during detention," he told a news conference. "He identified himself as a Sunni Muslim who had, and I quote, "hardened" his religious practice over the last 10 months. He said he'd been radicalised, on his own, via internet, and pledged allegiance - in writing and on film - at home with no contact with anyone else."
Ikken decided to attack police a few days before doing so and had left his Paris apartment on the morning of 6 June with that in mind, Molins said.
"Examination of CCTV footage in Paris and searches of his home, phone and computer, do not for the moment show he was linked to any third party," the prosecutor added.
IS loners' manual
Ikken had recorded a video pledging allegiance to IS and had planned to broadcast it on the Telegram encrypted messaging network but failed to do so, investigators have found.
He was shot by police while attacking a police officer from behind with a hammer and had been receiving treatment in hospital for a gunshot wound until Saturday.
Molins also confirmed that Ikken was an ex-journalist who was legally living in France as a student working on his doctoral thesis.