sentences:  Whether Karl Gabriel lived through World War I can never be known for certain, and even if it could, there is no proving that he was the Hinterkaifeck killer.Shortly after the death of his first wife in 1918, Lorenz Schlittenbauer was believed to have a relationship with Viktoria Gabriel and fathered Josef.The initials "L.S" appear on Josef's birth certificate, though these could be the initials of an attending doctor.