Three separate reasons were given—Lord Johnston described them as "hurdles": one was the issue of the fingerprint; the second was the forensic question, which could have been checked beforehand, of when the fingerprint was taken—the timing of the black powder or aluminium powder; and the third was the testimony of every single police officer who guarded the house at the scene of the murder, every one of whom went on oath to say that there was no way that Shirley McKie could have been in the house.In addition to the issue of the fingerprint, surely you interviewed all those officers, checked the issue of the black powder and the aluminium powder and ascertained that it was physically impossible for the print to belong to Shirley McKie.