France, Feb. 18 -- Deranque, 23, died from a severe brain injury after being attacked by at least six people last week in Lyon, on the sidelines of a conference by MEP Rima Hassan, of the hard-left party France Unbowed (LFI), at the university Sciences Po Lyon.

Prosecutors say six of the nine people detained on Tuesday are suspected of taking part in the beating, while three others were present during the arrests but are not suspected of assault.

Among those in custody is Jacques-Elie Favrot, a parliamentary assistant to LFI lawmaker Raphael Arnault. Favrot was arrested in the Isere region of southeastern France after being named by witnesses.

Arnault said the assistant had "ceased all parliamentary activities" and that procedures to t...