They are only snapshots but their impact could be ever-lasting. The images showing the moments after a policeman was shot dead on the Champs Elysee just three days before France votes for its next President. Campaigning ceased. But political opportunism did not. (SOUNDBITE) (French) FRENCH FAR-RIGHT PRESIDENTIAL CANDIDATE, MARINE LE PEN, SAYING: "For years, I've said what we have to do. I will say it once again, outline the battle plan that I have to protect the French people from this terrorist risk, which is by first of all controlling our national borders" Security and immigration have been central to Marine Le Pen's campaign. A poll taken before the shooting showed her support was slipping. But stock market jitters this morning suggest traders fear that could change. SOUNDBITE (English) MIKE INGRAM, MARKET STRATEGIST, BGC PARTNERS, SAYING: "You're seeing players buy protection on the euro, buy protection on the euro stocks. And yes, France specifically factoring in a higher premium on French bonds or indeed credit default swaps for the French sovereign." The preferred choice for markets is centrist Emmanuel Macron. The same survey that showed Le Pen fading, put him ahead. But after attacks on his security record by his rival, he's had to come out fighting. (SOUNDBITE) (French) FRENCH CENTRIST PRESIDENTIAL CANDIDATE, EMMANUEL MACRON, SAYING: "What they want is a collapse in morality, what they want is to watch us fall into ruin. I will not give in to this, do not play with fear." But even discounting the potential impact of the attack, there's no guarantee either candidate will make the runoff. Conservative rival Francois Fillon and hard-left candidate Jean-Luc Melenchon were seen as closing the gap. The shooting adding a tragic dimension to an ever more complex race.