Huge crowds and some 40 world leaders have gathered in Paris for a unity march after 17 people were killed during three days of deadly attacks.
More than a million marchers are expected to take the streets.
Police are seeking accomplices of the gunmen who attacked satirical magazine Charlie Hebdo and a kosher supermarket.
Ahead of the rally, a video emerged appearing to show supermarket gunman Amedy Coulibaly pledging allegiance to militant group Islamic State.
In the video, he said he was working with the Charlie Hebdo attackers: “We have split our team into two… to increase the impact of our actions.”
Said and Cherif Kouachi – who were shot dead by police on Friday – killed 11 people at the magazine offices in the French capital on Wednesday, and a policeman in a nearby street.
Coulibaly killed four hostages seized at the Hyper Cacher supermarket on Friday before being shot dead by police.
He is also believed to have shot dead a policewoman in Montrouge on Thursday, and has now been linked by prosecutors to the non-fatal shooting of a 32-year-old jogger in a park in Fontenay-les-Roses, in south-west Paris, on Wednesday.
His partner, Hayat Boumeddiene, is still wanted by police – although she is thought to have fled France last week. Officials believe she may have entered Turkey en route to Syria.
Jewish security raised
Sunday’s Paris rally is expected to dwarf marches across France on Saturday, when 700,000 people took to the streets.