An undated family handout, released by the French police headquarters on April 22, 2017, shows Xavier Jugele, the French policeman killed during the attack on the Champs Elysees Avenue in Paris, on April 20, 2017. French investigators were on April 22, 2017 probing the background of the jihadist who shot dead a policeman on Paris's prestigious Champs Elysees avenue as a jittery nation drew breath on the eve of the first round of a close-run presidential election. Candidates have clashed over how to protect France since April 20 night's shooting, which the Islamic State (IS) group claimed as the work of one of its devotees. / AFP PHOTO / FAMILY HANDOUT / FAMILY HANDOUT