LBJs mistress and JFKs wife both said it was Johnson.
Women know their men.
And you know it was an inside job because as the car corners the security detail is called off, to the protest of the security detail, by their boss in the car behind, so it would be a clean shot.
And as his car rounded the corner, Johnson got down on the floor of his car, before the first shot was fired. There’s photographic proof.