On April 20, 2017, Karim Cheurfi killed police officer Xavier Jugelé and injured two of his colleagues as well as a German tourist, before being shot down by return fire.
In the first instance, four men accused of having helped him obtain his assault rifle were tried.
Sentenced to ten years in prison while the National Anti-Terrorist Prosecutor's Office (Pnat) had demanded 18 years' imprisonment against him, Nourredine Allam, 32, is one of the two accused to appear again before the judges.
He is on trial for criminal association with a view to preparing a crime alongside Médérik Marinne, 29, the only accused acquitted at first instance and who appears free, under judicial supervision.
Accused of having sold a Kalashnikov to the killer, Nourredine Allam, described as a "small crook" by the investigators, had been tried at first instance for terrorist criminal association. But this qualification had not been retained by the court which had considered that the "simple fact of selling a weapon to a dangerous individual likely to kill police officers is not enough to characterize a terrorist offense".
As at first instance, the main question of the appeal trial will be to determine whether Nourredine Allam knowingly armed Karim Cheurfi. The prosecution had conceded that Nourredine Allam was not "radicalized" and that his only motivation was the lure of profit.
The Islamic State (IS) organization had opportunistically claimed responsibility for the attack, making a mistake in its statement about the identity of the assailant.
Tried for unauthorized possession of war material, Médérik Marinne, a former school animator and son of a police officer, was the only defendant acquitted at first instance. His fingerprints had been found on the killer's gun.
During his interrogations, he explained that he had touched the weapon "by accident" while he was in the company of Yanis Aidouni and Mohamed Bouguerra, the two men accused of having sold the Kalashnikov to Nourredine Allam and who, at first instance , were respectively sentenced to six years and five years of imprisonment.
These two men are not tried on appeal.
The trial is scheduled until October 7.