Over the last five years, a macabre mystery has been playing out on the South African coast. The carcasses of great white sharks have been washing ashore on local beaches with their bellies ripped open and their livers missing. What had killed the sharks was unclear, although scientists suspected orcas, also known as killer whales, which had been observed in the area.

Now drone and helicopter video footage has documented a pod of five orcas hunting and killing a great white shark in Mossel Bay, South Africa. The grisly video culminates with one of the killer whales gobbling up a large chunk of the shark’s liver.

CBC.ca notes that scientists have long suspected that killer whales have been hunting sharks off South Africa’s coast and driving them from their natural habitat. Now they have “irrefutable evidence,” says shark biologist Alison Towner.

“When I saw the footage, of course, it just confirmed everything,” Towner, a PhD candidate at South Africa’s Rhodes University, told CBC’s As It Happens host Nil Köksal.

“And as haunting it is to see the behavior, one can’t help but be awed by it as well. It’s really quite a novel piece of natural history to observe.”

Towner is the co-author of a new paper analyzing the footage, which was published in the journal Ecology.

Killer whales eating white sharks in Mossel Bay, South Africa