After a decapitated crocodile was found in northern Australia, the creepy case set social media alight with theories about who—or what—was to blame. Some suggested that a great white shark might have ripped the croc’s head off, while others ventured that a bigger, badder crocodile may have been responsible. “The one thing you can be sure of is that someone, not something, has taken its head off,” zoologist Professor Grahame Webb told The Guardian on Tuesday. “Whether they killed it and then decided to take its head, or whether they found it already dead can only be determined through an autopsy.” Crocodile photographer and conservationist Tom Hayes, who snapped the dead croc in Queensland after it was discovered, concurred that a human was to blame. Hayes said the corpse had cut marks that looked like they’d been caused by a machete, and several of its body parts, including its nails, had been removed along with the head. “If it was another crocodile, it would tear it off from the least-resistant point at the spine just above the shoulders,” Hayes said. “[T]his was obviously surgically removed from the base of the [skull].”