CANBERRA, Australia (AP) — An Australian crocodile farmer who found an orthopedic plate inside a croc's stomach said Thursday that he had been told the surgical device was from a person's body and had been contacted by relatives of missing people anxious for clues.

Koorana Crocodile Farm owner John Lever found the plate inside a 4.7-meter (15-foot-5-inch) croc called M.J. during an autopsy in June at his business near Rockhampton in Queensland state.

He initially wasn't sure if the unusual find had been part of an animal or human. But he said since making photos of the plate public, he had been told it was a type used in human surgery.

Lever estimated that M.J. was 50 to 70 years old when he died. M.J. could have eaten the bone that the plate had been attached to by six screws 50 years ago, he said.

All remnants of human tissue attached to the plate had been long digested before M.J. died several months after losing a fight with another croc.

Lever later said that Queensland police had told him they had opened a missing person investigation and asked him to bring the plate to the Rockhampton station on Friday.

A police spokesman told The AP he could not comment.

Lever is continuing to make inquiries in the hope of discovering what decade the type of plate was used and perhaps who it had belonged to.

"I wouldn't call it an investigation, we're making inquiries because we're fascinated by this whole thing," Lever said. "Obviously this crocodile has chomped on something and that plate has been left in its stomach complete with screws."

Lever bought M.J. from a farmer in Innisfail, 1,000 kilometers (600 miles), north of Rockhampton, six years ago. Sometime earlier, M.J. had been trapped in the wild. Crocodiles are protected in Australia and are only trapped if they are a threat to humans.

"We've had a couple of people get in touch with us about their relatives that have gone missing in the northern Queensland area and they're anxious to find out — there's been nothing heard of these people, they've just disappeared," Lever said. "We'll certainly keep these people informed of any new news that we can get."

The last fatal crocodile attack in Australia was in October when a woman was snatched while gathering mussels with her family in a waterhole in a remote part of the Northern Territory.

The last fatal attack in Queensland was a year earlier, when a 79-year-old dementia patient was killed after wandering from a nursing home at Port Douglas.

The crocodile population has exploded across the country's tropical north since the 1970s. Because saltwater crocodiles can live up to 70 years and grow throughout their lives — reaching up to 7 meters (23 feet) in length — the proportion of large crocodiles is also rising.