However, the claims for 15 September 1942 are in serious doubt, following the first detailed scrutiny of the records of individual Allied squadrons by Australian historian Russell Brown. Moreover, Brown lists three occasions on which Marseille could not have downed as many aircraft as claimed. Christopher Shores and his co-authors wrote that Marseille over-claimed on occasion, particularly in September 1942. They concluded Marseille had developed such a supreme confidence in his ability his mentality dictated, "If I fire at it, it must go down." They estimate two-thirds to three-quarters of his claims were aircraft that were destroyed, crash-landed or at least were heavily damaged.