More than two years ago, Brisbane private schoolgirl-turned-working professional Kathleen Riethmuller mysteriously vanished from Sydney without a trace.
Haunting CCTV shared by police showed Ms Riethmuller, then 28, strolling into a Bunnings store in Artarmon, in the city’s north, wearing a denim dress around 11am on October 28, 2021.
A few hours later, her belongings including her ID and bank cards were found abandoned 7km away inside a backpack in a Lane Cove street.
Further inquiries revealed the data scientist was seen exiting a car at a petrol station at 2.30pm. That was the last time she would be seen.
When she was still unaccounted for three months later, Ms Riethmuller was declared a long-term missing person by the n Federal Police – and she remains on that list to this day.
Now, fresh details have come to light about the erratic and peculiar last known movements of Ms Riethmuller in the hours before she disappeared.
Kathleen Riethmuller, 28, (pictured right) mysteriously vanished from Sydney’s northern suburbs more than two years ago
Now, fresh details have come to light about the erratic and peculiar last known movements of Ms Riethmuller in the hours before she disappeared
Police have also revealed that while the data scientist’s case was initially considered a case of self-harm, detectives now believe she disappeared on her own accord and may still be living in disguise within n society.
The fresh details come after Daily Mail previously revealed Ms Riethmuller tried to flog off items on Gumtree in the weeks before she disappeared and one of her Facebook accounts later mysteriously deactivated.
In the first episode of Channel Nine’s Missing Persons Investigation, Detective Sergeant Gavin Franklin said the desperate search to find Ms Riethmuller unfolded when a member of the public discovered her abandoned bag.
Inside, police found her passport, birth certificate, mobile phone, reading glasses, hairdryer, underwear, toiletries and wallet – containing her bankcards, Medicare cards, and other important documents.
Alarmingly, detectives also found a receipt for two 50m bundles of rope that she had purchased that morning from the hardware store.
Officers immediately tracked down Ms Riethmuller’s mother, who informed them she hadn’t heard from her daughter for a month.
The evening before she disappeared, Ms Riethmuller spent the night at The Sydney Boulevard Hotel (pictured) in Woolloomooloo with a stranger
CCTV footage captured her leaving the building at 8am on October 28 – the day she disappeared
A ‘jittery’ Ms Riethmuller checked into Elephant Backpacker (pictured) in inner-city Woolloomooloo the morning she disappeared
Her mother added that Ms Riethmuller had been feeling isolated, struggling with not having friends and had recently lost her job.
Concerned for Ms Riethmuller’s welfare, officers rushed to her apartment to see if she was home before spending the night searching a massive bush reserve near her last known sighting.
The next big breakthrough in the case came days later when a member of the public, Shane, came forward to tell police he had seen Ms Riethmuller running erratically through a suburban street in Riverview and offered her a lift.
But during the journey, Ms Riethmuller, who no longer had her backpack or the rope, abruptly jumped out of the moving vehicle – into four lanes of oncoming traffic – and disappeared into bushland.
She later emerged and got back into his car, before he dropped her off at the petrol station.
Shane said her behaviour made him feel as though she was in trouble or ‘running from something’, but when he asked her, she said everything was fine.
Operating off another tip, police later learned Ms Riethmuller, after leaving Bunnings, had travelled 27km away to Parramatta, in the city’s west, where she was captured on CCTV inside a McDonald’s store.
Another man also came forward to reveal he had spent the night with Ms Riethmuller before she disappeared.
CCTV footage captured Ms Riethmuller walking out of Bunnings Artarmon with two bundles of rope around 11.40am
She then headed 27km west to Parramatta, where security vision picked her up inside a McDonald’s (pictured) at 12.30pm
Pictured: Centennial Avenue at Lane Cove, where her backpack was found by a member of the public sometime between 1pm and 2pm
Inside the backpack, detectives found Ms Riethmuller’s passport (pictured) along with her phone, ID cards, bank cards, clothes, toiletries and a hair dryer – suggesting she was living out of that bag
The 26-year-old said they met while he was in Kings Cross, looking for a place to stay, before the duo went somewhere to have a drink.
They ended up at The Sydney Boulevard Hotel, where they spent the night together in one of the rooms.
He said the pair were not intimate and he left the hotel the following morning to go to work. Ms Riethmuller was seen leaving the hotel at 8am that morning, with a massive black suitcase and her backpack.
Police examined her bank records and discovered she had withdrawn $2,200 – almost all of her savings – shortly after leaving the hotel, from a nearby cashpoint.
The discovery turned the case on its head as police began working on the assumption Ms Riethmuller was not in danger, but rather had chosen to disappear of her own accord.
In light of the new information, Detective Sergeant Franklin returned to Ms Riethmuller’s apartment to collect items – including her computer and several journals – in a bid to find clues as to her state of mind.
It was evident Ms Riethmuller had not been inside the unit for a long time as there was expired food in the fridge and a rubbish bag on the kitchen benchtop, which had attracted flies.
Back at the police station, detectives scoured Ms Riethmuller’s journals and uncovered a series of insightful entries suggesting she wanted to ‘go off the grid’ and ‘remove any trace of her’.
‘She made a number of comments about leaving no traces, closing old bank accounts, the need to cover up IP addresses, paying for the records to go, paying things with cash, [having] no friends from before, [and that] no one can know a thing,’ Detective Sergeant Franklin said.
Ms Riethmuller said she worked in ‘data science, innovation and market developments’ with ‘experience in consulting, finance and start-ups’ on her online profiles
Photos on her laptop showed Ms Riethmuller frequently changed her appearance – a skill that detectives believe she may have employed to disguise her identity
‘She also made notes in there that she wanted to go to Melbourne. Wants to start a new life.’
Detective Sergeant Franklin said police believe Ms Riethmuller may still be living in the community under an assumed identity.
‘We know that Kathleen felt isolated and we know that she had a few struggles, perhaps she just wanted to have a clean state, start afresh,’ he said.
‘She could of cut her hair, purchased new identification. She may be out there… working with someone under a different name.’
Police have scaled back the search and are monitoring for any new leads into Ms Riethmuller’s new identity.
According to a blurb on the AFP missing persons register, Ms Riethmuller is known to use the aliases Amy Munroe, Kate Riethmuller, Margaret Riethmuller and Kate Muller.
Detective Sergeant Franklin said that if Ms Riethmuller is out there he wants her to know it is not a crime to go missing and urged her to walk into a police station and let officers know she is safe.
Anyone with information which may assist in locating the whereabouts of Ms Riethmuller is urged to call Crime Stoppers on 1800 333 000.
For confidential support, contact Lifeline 13 11 14 or Beyond Blue 1300 22 4636