Fourteen people have gone to trial in Paris for their alleged involvement in the 2015 attacks on the French magazine Charlie Hebdo and a Jewish supermarket.
The suspects, going to the docks on Wednesday, are accused of providing logistical support to the gunmen and could face 20-year sentences.
Three are being tried in absentia as they are believed to have fled to Iraq and Syria, where the Islamic State group at the time declared their "caliphate".
The attacks spanning three days in January 2015 started at the satirical magazine Charlie Hebdo, which regularly depicts the Prophet Muhammed, which some Muslims find blasphemous.
The brothers Said and Chérif Kouachi opened fire on their editorial meeting on January 7.
They killed 12 people, including France's most famed cartoonists and police officers.
A day later Amedy Coulibaly shot and killed a police officer and killed four Jewish men at a kosher supermarket.
The three gunmen were killed in separate police standoffs.
The slogan, Je suis Charlie, (I am Charlie) went viral and a wave of anti-terror marches took place.
The biggest rally was in Paris, with global leaders showing their support.
Six African heads of state were at the march.
But with Boko Haram and more frequent jihadist attacks in Africa, some questioned why their leaders did not show the same support back home.