Oxford appeared to be oblivious for most of the proceedings. The prosecution presented much eyewitness evidence, while the defence case consisted of various family members and friends who testified that Oxford had always seemed of unsound mind, and that both his grandfather and father were alcoholics who had exhibited signs of mental illness. This carried a great deal of weight, as it was thought during this time that both drink and hereditary influence were strong causal factors for insanity. Oxford's mother testified her late husband had been violent and intimidating, and that her son was not only prone to fits of hysterical laughter and emitting strange noises, he had been obsessed with firearms since he was a child. Various eminent pathologists and physicians testified that due to "brain disease" or other factors, such as the shape of his head, Oxford was either a mental imbecile or simply incapable of controlling himself.