A 3,000-year-old cold case could be the earliest known victim of a shark attack. The skeleton, found in Japan, is covered in unusually deep cut marks. It looks like the victim of a frenzied samurai sword attack, but could his wounds have been caused by a shark? If so, which species of shark is the prime suspect? Shark experts Alyssa White, Gavin Naylor, Kirin Sekito and Masato Nakatsukasa investigate.