Radouane L received a suspended prison sentence in 2011 for carrying a forbidden weapon and a one-month sentence in 2015 for consuming drugs and obstructing police, Francois Molins said.
He had been put on a national security watchlist in 2014 "because of his radicalization and his links to the Salafist movement," Molins added.
"In 2016 and 2017 he was the object of an effective follow-up by the intelligence services which revealed no warning signs that could indicate a possible act of terrorism," Molins said.