Adolf Hitler’s self inflicted bullet wound to the head and suicide has been called into question after US researchers claimed that the skull fragment believed to have belonged to the Nazi dictator is that of a woman.

The four-inch long skull fragment features a hole which would appear to have been made by a bullet as a projectile reportedly had passed through Hitler’s left temple at the time of his suicide. The skull piece had been kept by Russian authorities in federal archives along with what are understood to be his jawbones. Together, the bones represent all that is left of Hitler’s corpse, the charred remains which invading forces first recovered at the end of the war in 1945. For decades, Russian authorities have held up the skull fragment as proof that the Soviet army discovered Hitler’s body amongst the ruins of Berlin and that he killed himself on April 30 by combining a gun shot to the head and a cyanide capsule.

But a History Channel documentary called Hitler’s Escape says the bone is that of female under 40 years of age and not that of Hitler, who was 56 when he allegedly died. The programme features Nick Bellantoni, an archaeologist and bone expert who made DNA tests at the University of Connecticut. He and his colleagues doubt that the skull fragment could have belonged Hitler’s long-time companion, Eva Braun, since it is understood that she had committed suicide by taking a capsule of cyanide rather than with a gun.

The recent test result are likely to revive old conspiracy theories which propagate the idea that Hitler did not commit suicide in 1945 but rather survived and escaped to South America or elsewhere. Proponents of that concept believe only his body double had been found.

However, Russian authorities have never held up the skull fragment as exhibit one, always claiming that the jawbones — which are in perfect condition – are proof that the dictator died in 1945. Soviet forces found an assistant to Hitler’s dentist who confirmed they are authentic. The controversial skull fragment was found in 1946, when the Russian authorities began investigating rumours that Hitler was living. The skull fragment was discovered in the same hole where his charred remains had been found.