Expedition Unknown season 15 episode 6 aired on July 23, 2025. The episode titled Shark Files featured Josh Gates exploring exciting yet dangerous incidents related to sharks.One of the incidents he dived into was about a tiger shark and a murder. In an aquarium, there was a great white shark. However, its behavior was somehow unexpected. As the shark looked sick and even refused to eat, it soon vomited a severed human arm. It shocked everyone.Narrating the incident, Expedition Unknown's Josh shared:"But this shark doesn't seem all that threatening. In fact, it looks sick. It refuses to eat and prowls the water slowly, rubbing its body against the walls of the enclosure. Then something terrifying happens. The shark convulses violently, and then, in a sickening spectacle, vomits up a putrid brown cloud, a stew of half-digested horror containing a human arm."Expedition Unknown season 15 episode 6: A great white shark and a murder mystery View this post on Instagram Instagram PostThe latest Expedition Unknown season 15 episode covered Shark Week. Show host Josh Gates explored a mysterious incident featuring a shark with strange behavior. The great white tiger shark was from one of the aquariums.Stating the facts and how its name came into existence, Josh explained:"Named for the distinctive striped pattern on their backs, they're the second largest predatory shark on the planet, growing to over 16 feet in length and weighing as much as 2,000 pounds."However, as things unfolded, everyone noticed strange behavior from the shark as she looked sick. She even stopped eating and was seen rubbing her body against the walls, which was unusual. As Expedition Unknown's Josh described it, it was a "sickening spectacle." View this post on Instagram Instagram PostThe great white tiger shark vomited, and among the contents from her stomach was a "half-digested" human arm.Soon, the police arrived and collected the evidence. At first, they thought that it belonged to an "unlucky swimmer." However, later on during the investigation, it was revealed that it was a male left arm. The pattern of the arm's severance, just above the elbow, did not seem like the work of a great white shark.Further, it should have been digested in the shark's stomach, as they have a powerful digestive system. View this post on Instagram Instagram PostAdditionally, the arm was in "near-perfect" condition. That was when the authorities learned more about it."When examiners inspect the actual wound, something doesn't add up. It's not messy enough. A tiger shark's 48-curved serrated teeth are designed to rip, tear, and shred," said the Expedition Unknown host.Seeing how the severed marks were "clean" and "almost precise," things did not add up. The edges of the severed arm seemed as if they were cut by a knife. It was clear that it was not done by a great white shark.Investigators learned that the arm was cut off before the shark ate it. They reached the conclusion that it was not a work of a "killer shark" but a "killer human."To know more about the incident, fans can stream Expedition Unknown season 15 episode 6 on Discovery+.