The blood from at least four individuals other than Ötzi on his equipment indicated that he had been in violent contact with multiple people in the period before his death. The pattern — different blood sources on the knife versus the arrow versus the coat — was consistent with Ötzi having been in a fight in which he inflicted wounds on multiple opponents before dying himself.
The defensive wound on the right hand, with its trajectory of healing, placed a hand-to-hand encounter several days before the arrow attack. The two events were therefore separate in time: a close-quarters fight that Ötzi survived with a hand wound, followed days later by an ambush killing.
Horn’s conclusion was that the most likely scenario was a targeted killing — someone who wanted Ötzi dead and had the opportunity to shoot him from behind. He explicitly noted that the copper axe’s not being taken was evidence against opportunistic robbery, though he acknowledged that other scenarios — the killer was interrupted, the killer did not want the axe, the killer died in the same encounter and could not carry anything — could explain its presence.
No scenario can be proven. Horn’s analysis represents the application of modern investigative methods to a case where the physical evidence is five thousand years old, the witness pool is exactly zero, and the jurisdictional, social, and political context of the crime is known only in outline. What the forensic analysis can establish is what is consistent with the evidence; what it cannot establish is what actually happened.