The personal effects left behind by the numerous victims, as well as the diary written by the murderer himself as a form of boasting, and the manuscript prepared by that reporter based on the murderer's narrative, all these contents were enough to prove the fact that the murderer committed the killings.
Although the diary and manuscript could be dismissed as fantasy, the numerous victims' belongings were indisputable crucial evidence, sufficient to secure a conviction and bring this extremely vicious criminal to justice.
Moreover, after Kojo Kyoko cut off three fingers from the reporter's right hand, he confessed everything he knew, just like spilling beans from a bamboo tube, even handing over the most critical piece of evidence he controlled, a toy ball, turning this extremely heinous serial murder case into an ironclad one.
