According to their results recently published in the journal Ecology and Evolution, the culprit is clear: a killer whale fatally assaulted the over-15-foot-long shark, then proceeded to devour its innards. While it most likely zeroed-in on the nutrient-rich liver, multiple scavengers also got in on the meal.

Great white sharks are washing up dead on beaches with enlarged brains in what is becoming a spiralling marine mystery.

In more than 30 years of monitoring, Canadian wildlife agencies never found a single dead great white shark. Then, in the course of a year, five washed up – and nobody knows why. The Canadian sharks join four previously found dead in US waters – all under similarly perplexing circumstances.

Scientists said the presence of killer whale DNA on the great white shark was the result of a "true predation event".

Faced with a rash of shark deaths marked by brain swelling, Canadian and American scientists are trying to solve a marine mystery.