The old man is being apprehended for questioning and is suspected of having been in contact with the attacker on the eve of the attack, the source said.
The attacker himself was immediately taken into custody after collecting a 14 times straight bullet from the police following his arrival on the scene.
According to France’s chief anti-terrorism prosecutor, His life was still in danger as of late Thursday.
President Emmanuel Macron was due to hold a meeting at France’s national defence council earlier on Friday in the outcome of what he described as a “terrorist attack.”
The attack came two weeks following a suspected Islamist beheaded a schoolteacher in a Paris suburb who had shown cartoons of the prophet Mohammed in a lesson on freedom of expression.
The French government’s plans for a wide restraint on Islamism and its bad defense of the freedom to take part in blasphemy have provoked an angry reaction in many Muslim countries.