The remains of an American woman have been discovered inside the stomach of a shark after she disappeared on vacation in Indonesia while on a diving trip, according to a friend of the woman.

Colleen Monfore, 68, was diving with friends near the Pulau Reong island off the coast of Indonesia’s Southwest Maluku Regency on Sept. 26 when she did not resurface, Asia Pacific Press reported.

Two weeks after Monfore disappeared in the tropical waters, a fisherman spotted a shark in distress and killed the creature. Upon cutting open the shark’s stomach, the fisherman uncovered what were believed to be Monfore’s remains along with her wetsuit and bathing suit.

Initial reports indicated the shark had attacked and eaten Monfore, but a friend of the Michigan woman says that the evidence so far suggests this is likely false.

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Colleen Monfore

Colleen Monfore, 68, was diving near the Pulau Reong island off the coast of Indonesia’s Southwest Maluku Regency on Sept. 26 when she did not resurface. (Asia Pacific Press)

Kim Sass, who wrote that Monfore was her "very good friend" in a Facebook post, listed what is known about the case, and how it appears likely that Monfore died of a medical issue during a dive.

Sass wrote that the fisherman captured the shark around Oct. 4 near Timor-Leste, a southeast Asian country which is 70 miles away from the dive site where Monfore vanished over a week earlier.

fisherman standing over body of shark on beach

The fisherman who caught the shark said he found the shark in distress and killed the creature. He cut open the shark's stomach and found human remains, a wetsuit and a bathing suit. (Asia Pacific Press)

Monfore’s remains were identifiable, according to Sass, which would not have been had the shark eaten her at the time she went missing.

search and rescue teams searching

Rescue teams searched for Monfore in the tropical waters.  (Asia Pacific Press)

While it can take days for sharks to fully digest a meal, the stomach of a shark "produces an acid that is strong enough to dissolve metal," while "large bones and other indigestible objects are prevented from going past the stomach due to the small size of the opening to the intestine," according to the Hawaii Department of Land and Natural Resources.

Sass believes that the nearly eight-day timeframe from when Monfore disappeared to when the shark was found suggests that the shark consumed Monfore after she was already dead.

"Colleen's body was identifiable. Her fingerprints (again identifiable) are being used by our US Embassy and the local government for proof of death," Sass wrote. "This would not be possible if the shark had attacked her weeks ago."

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Sass said that dive information, photos and witness accounts from two other divers and the group’s dive master show that Monfore was in 24 feet of water when the group turned around due to a change in the current. Sass added that Monfore likely had half a tank of air at that time.

"There was a down current at the turn around site, but it was manageable," she wrote. "I've easily done 1000+ dive with this gracious woman; she was an excellent diver. I don't believe it was the environment and certainly not a shark that ended her life."

It remains unclear how exactly Monfore died. 

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Indonesian authorities are continuing to investigate.