N’s fountain pen was found in Ishikawa’s kitchen on a shallow shelf above the door. The public prosecutor used this, along with Ishikawa’s confession, as key evidence that Ishikawa wrote the ransom note and committed the crime. However, there are a number of inconsistencies regarding the pen: For one, the ink it contained did not match the ink on the ransom note or the ink that N used. Neither the victim’s nor Ishikawa’s fingerprints were found on the pen. Furthermore, the pen was not found until a month and a half after the crime was committed, despite two full inspections of the house. Despite these inconsistencies, the court stated in 2005 that the fountain pen did not constitute a point for further investigation because the back portion of the doorframe was clearly easy to overlook.