A total of 14 people are set to face trial in France over the beheading of a teacher by an Islamist extremist in 2020, a crime that shocked the country, legal documents obtained by AFP showed on Tuesday.

The most serious charges -- complicity in a terrorist murder -- are being pressed against two friends of the Chechen refugee who murdered teacher Samuel Paty after he showed pictures of the Prophet Mohammed to his pupils, the case documents reveal.

The killer, 18-year-old Abdullakh Anzorov, was shot dead by police at the scene in the Paris suburb of Conflans-Sainte-Honorine.

Prosecutors believe his friends, Azim Epsirkhanov and Naim Boudaoud, accompanied Anzorov to buy a knife and Boudaoud travelled with him to the school.

Another six adults will be tried for associating with terrorists, including the father of a girl at Paty's school, an Islamic preacher, as well as a Muslim convert in contact with Anzorov via Twitter.

Six teenagers will be brought before children's courts for allegedly undertaking surveillance around the school and identifying Paty for his killer.

Paty was targeted after messages spread on social media that he had shown cartoons of the Prophet Mohammed from the satirical magazine Charlie Hebdo to his class. 

The 47-year-old history and geography teacher had used the magazine as part of an ethics class to discuss free speech laws in France where blasphemy is legal and cartoons mocking religious figures have a long history. 

Paty has become a symbol of France's fight to maintain its strict secular values, with President Emmanuel Macron calling him a "quiet hero" of the republic.