Friends of an American tourist eaten by a shark while diving off the coast of Indonesia have revealed a new theory into the tragedy.   

Colleen Monfore, 68, a retired mom of two from Michigan, was just beginning her seven-week diving tour with her husband , Mike, when she went missing in the ocean near the Pulau Reong island on September 26.

Authorities say she was diving with six friends and a tour guide when a strong current dragged her away at around 9am local time. The guide was unable to pull her back into the boat. 

Rescue teams searched for eight days before finally giving up on October 3 due to the dangerous conditions at sea and the low chance of finding her.

Then, on Sunday, a fisherman in the neighboring country of East Timor found human remains in the belly of a shark.

Authorities have since been able to confirm the remains were that of Monfore from her fingerprints, Rick Sass, a longtime friend who has been in contact with her family, told the New York Post.

But he and his wife are adamant that Monfore, whom they described as an experienced deep-sea diver, was not killed by the shark.

'We do not believe this was a shark attack,' Sass said. 'Mike thinks she suffered some kind of medical issue in the water.'

He said he and his wife, Kim - with whom he ran a dive shop for more than 40 years - examined photos from the dive, spoke with Mike at length about the incident and reviewed data from his dive computer.

They now say Monfore was separated from the group when they hit rough waters, forcing them to turn around.

Monfore was likely around 24-feet-deep at the time and probably only had half a tank of air left, Sass said.

'There was a down current at the turnaround site, but it was manageable,' Kim wrote on Facebook, noting she has 'easily done 1,000+ dive[s] with this gracious woman.

'I don't believe it was the environment and certainly not a shark that ended her life.'

Rick added that Monfore and her husband 'dove massive numbers of trips with us over 30 years' including to Bali, the Philippines and Bikini Atoll.

'She knew what she was doing.'

Mike had already been an avid diver when he met Colleen in high school in their native South Dakota, and she too, fell in love with the ocean.

The two went on to have two children and eventually four grandchildren, but Sass said they never stopped traveling the world and exploring the seas together.

'They were both retired and really enjoying life,' he said.

'We used to call her "Saint Colleen,"' he added. 'She was an amazing woman. She loved nature and animals.

'I know she would never have wanted a shark to be blamed for this tragedy.'

Sass noted that shark attacks against divers are extremely rare.

'We've dove with hammerheads, tiger sharks, bull sharks,' he said. 'You have to give them respect and be cautious but they won't just attack you.' 

Shark attacks are extremely rare in Indonesia, with only 11 unprovoked attacks reported since 1749, according to the latest International Shark Attack File data, which was published earlier this year. 

Before the case involving Monroe, the last reported shark attack in Indonesia occurred near Bali in July 2022 when Russian surfer Sasha Utkina was bitten by a small shark. She suffered lacerations to her foot and was treated at a local hospital. 

The regions in Indonesia with the most reports of shark attacks are the Riau Islands and East Nusa Tenggara, records reveal. 

Now, Sass said, Mike is struggling not only with Colleen's sudden death, but also with trying to get her remains home.

'He's hardly been sleeping at all, partly because he's up on the phone with Indonesia, which is a 12-hour time difference.

'He's answering phone calls in the middle of the night and talking to us during the day, and... just not being able to sleep because of this horrible thing that happened.'

Authorities in Indonesia say they are investigating the incident.