Kathleen Riethmuller is Missing
If you have a loved one missing, I just want to wish you the best. Research shows how ambiguous loss is so devastating and the grief so unrelenting.
The disappearance of this young software developer, from Queensland, is to me a particularly puzzling event. I didn’t know Kathleen but in many ways she is just like any number of my friends and colleagues and family members. I’m certain there is more knowledge out there and I would dearly wish to see this mystery resolved.
What happened to Kathleen Riethmuller?
October 28, 2021, Kathleen disappeared. Here’s the national missing person’s page — though it’s light on details and can’t even spell her name consistently: Kathleen Riethmuller | National Missing Persons Coordination Centre
Timeline of events
- Thursday October 28, 2021:
- 8am Left the Boulevard hotel, 90 William St, carrying a backpack, a bag, and with a large black suitcase on wheels.
- 9:30am Paid for a budget room at the Elephant Backpacker hostel, Sir John Young Crescent, Woolloomooloo. "I checked her in and gave her the keys, she paid for a budget room, she was jittery and twitchy, that's why I remember her," manager Nick said.
- ~ 10am -- withdrew 4 amounts of money, "almost all of her savings" according to people. (I think 4 * $2200 dollars, but could've been 4 amounts totalling $2200)
- 11:40am Captured on CCTV at Bunnings Reserve Road, Artarmon. Blue denim dress, backpack, face mask. Purchased 50 metres of rope. Evidence from receipts found in backpack and subsequent CCTV footage
- ~12:20am - Capture on CCTV at Paramatta McDonald's -- Blue denim dress, backpack, face mask, carrying the 50 metres of rope and mobile phone in her hand. (receipt for this found in her bag)
- 2pm Kathleen’s backpack was found along Centennial Avenue in Lane Cove
- "Also Thursday afternoon, but later" - Kathleen's phone was found, separately, in Lane Cove North. (There's three different reports of where the mobile phone was located. In the channel 9 missing person's show they say that it was found in the backpack. But an acquaintance states the phone was disabled and found near the bunnings in Artarmon (see Websleuths link). Elsewhere it's stated that it was found in Centreniial Avenue Lane Cove, by a different person than the person who found the back pack.
- ~ 2:20pm - Kathleen was seen sprinting along the middle of the street, over a hill in Riverview. Member of the public Shane offered her a lift. I think this was close to the intersection of Taleeban Rd and Wangalla Rd.
- Minutes later - with Shane, while paused at the T-junction of Warrarron Rd and River Rd West, Kathleen hastily exited the vehicle and ran across the road, unperturbed by the danger from 4 lanes of traffic -- cars screeched to a halt etc. She disappeared into the bush. Shane waited briefly -- and she re-emerged soon after -- waved at him -- and resumed travelling with Shane.
- ~ 2:40pm - Shane dropped off Kathleen at the Speedway on the corner of Miller St and Falcon St, Cammeray NSW. Given that she'd said she wanted to be dropped at a park, and this was diagonally opposite a large park, and CCTV showed her to immediately proceed in the direction of the park -- we'd say she was headed toward St Leonard's park. CCTV shows that at this point she had no backpack, no phone in her hand, no rope, seemingly no possessions at all. No further confirmed sightings.
- 6:30pm (two unconfirmed sightings) - sitting under the hunter's hill underpass on Burns Bay Road
Final Unconfirmed Sightings
From a reddit thread (link in references):
Vague and mysterious wording from police here... why do they talk like this??
Ms RIETHMULLER is known to use the aliases Amy MUNROE, Kate RIETHMULLER, Margaret RIETHMULLER and Kate MULLER.
How and in what circumstances were those "aliases" used?
Kate isn't an alias, it's a common diminutive form of "Kathleen" (as is Kat).
Deliberate change of identity
The following was written before I saw extra information available in the channel 9 show "Missing Person's Investigation" episode 1.
Police have left open the possibility that Kathleen deliberately disappeared. 🤦♂️
Before I saw the show "Missing Person's Investigation" I thought the following:
... there’s various errors and misconceptions that allow them to think this ... I consider it very unlikely.
And I gave these examples of things which I've seen possibly seen mentioned in comments at any site (reddit, facebook, websleuths, media reports)
None of these are "direct" quotes of a specific person. They're more intended to convey the vibe, or the theory, that some of these comments or reports touched upon.
"Her gumtree items for sale were deleted a week after she vanished… so she must've done that, right?"
— No, it happens automatically.
"Someone with her name created a linked in account 6 months later in Rockhampton!"
— So what? There are multiple people in Queensland with her exact same formal first and last name, even if different diminutive forms are often employed. It's not hard to find more info about which K.R. in the Capricornia region, this probably is. And 90% chance it's them, or 10% chance that either the K.R. born ~ 2000 in Brisbane, or, an entirely different K.R. from the Northern Territory has moved to the Greater Rockhampton Area.
That it is KAR, the 28 in 2021 Data Scientist: No, it's not and would fit no theory for it to be her, in any case.
"She was a data scientist, therefore, you know, hackers and the dark web and stuff?"
She could've disappeared from the grid! Logged out of the "system", she could be living off bitcoin
Knowledge of how to use digital currency without being detected by the five eyes countries: is not a standard Data Science subject. Data Science is a combination of engineering and statistical mathematics. It does require a high level of skill and cognitive development in particular ways. But a professional data scientist isn't automatically able to perform acts of subterfuge. It's romantic! It would be wonderful if it were true. I desperately WANT it to be true. But this is the fundamental resistance I have to the idea. The idea is itself attractive. That's why we should be careful not to assign a higher probability to it than it deserves on its merits.
Digital currency is both good and bad for anonymity. I don't have the latest facts, or any specific knowledge in the field. Around that time crypto was big news. The market cap of cryptocurrencies had recently surpassed $2 trillion. That's a lot of "Illions". See? Already I am starting to make reasons why she might have wanted to dabble in crypto.
She didn't read books on Crypto. Ok, let's say she did -- but she did not save them on Good Reads. Ok, sure. In that case we're saying she had good -- no perfect -- operational security. Clearly she would've had a long term interest in security, to have develop such high level talents, that even mega succesfull people such as crypto-criminal "Dread Pirate Roberts" -- and in her entire past, she's had many many interests, but not once has she had an interest in even White Hat security techniques, nor any interest in the history of hacking, of neo-liberal anarchist economics, or any adjacent field.
With a few tiny exceptions. Let's look at those.
I had better look into using an API to download the list of all the books in her many good reads category.
Checking if they have an API, I found:
"As of December 8th 2020, Goodreads is no longer issuing new developer keys for our public developer API and plans to retire these tools."
Never mind. I revert back to an old technique, similar to this old blog post:
And use the dev tools to get the lists of books. I really want the "subjects" of the books, and in this instance I'm interested in the non-fiction books.
"She was known to use aliases."
— Yes. A young woman protecting her anonymity on dating sites (for example) means she’s navigating a dangerous world, has nothing to do with fraud/vanishing.
"She was unemployed and may have gone to Melbourne to seek employment."
— Her resume and identity are crucial to that. She wouldn’t leave those!
But on the question of could she restart her careeer with a different name? If we magic away the problem of getting a new identity, and establishing a new identity for banking purposes etc. If we reduce the problem down to this:
Challenge: "Is it conceivable that KAR could've landed a new data science job, in a new city, without a resume, and without relying on any past references?"
Here's the thing. I have to reluctantly say... Yes. It is conceivable. It might've been an interesting challenge. And already I'm starting to fall into the trap of "What if?"
If she did do such a thing -- it would be easier if it was a "purely offsite" role. But not necessarily so. Just easier to avoid re-identification.
"She had a good reads category called fiction-2022 and it has 5 books in it! So she must be alive and still using that account!"
-- No! The last activity on her account was 8th July 2021. The category probably means "fiction I intend to read in 2022".
"She was reading a book called: 'The Million Dollar Mindset: How to Harness Your Internal Force to Live the Lifestyle You Deserve' Obviously.... she decided to change her identity!"
-- No... unless the book was called "How to change your identity" this is just apophenia.
Even if the book was called "How to disappear" you'd have to do a Bayesian analysis of how many people read that book versus how many of them did actually disappear. It's all just reaching.
The "disappeared on purpose" theory must explain the "checked into a hotel" and "bought rope" and "discarded her bugout bag.".
If the theory is extended to say that she did those things to "throw people off her tracks" or "create an impression that she was intending to commit suicide..." it is a very tenuous argument.
Wouldn't it be easier and far more reliable, to create a suicide note?
If we're saying she was acting rationally, in charge of her faculties, and deliberately did these specific things as part of a plan to disappear: you're deceiving yourself. You're arguing she was rational enough to successfully disappear without a trace, but irrational enough to leave behind erratic behaviour with no clear purpose.
Here is what I originally said next:
"The argument defeats itself."
But already, I am starting to wonder.
Am I just another person hooked in by the curse of the intriguing?
(People love to consider strange theories. That’s something I love about humans. What I don’t love is that we then go ahead and believe these strange theories. Here is one example, tenuously related as it pertains to a woman who disappeared in Sydney in 2021: Melissa Caddick disappeared while owing people a lot of money, and several months later her foot (still in its shoe) washed ashore, 500kms away. People hypothesised that she may have cut off her own foot, in order to trick people into thinking she was dead. Ok. Get it together people. While it's a theory worth considering it can be quickly ruled out. It’s a very big price to pay for a single forensic red herring. Having the foot turn up two months later and 500kms away is not the way you want such an expensive red herring be found. A cheaper red herring would've been, for example, to leave a suicide note. No one in their right mind, capable of successfully changing their identity and disappearing without a trace, thinks, "Hmmm, I could write a letter, or, you know what, I might just cut off my foot instead." Later, a coronial enquiry wisely reached the only sensible conclusion: Melissa was dead.)
Abduction by a stranger
(It hurts to even type these things out, as I feel for anyone who knows Kathleen who might read this.)
I believe there is a significant possibility that Kathleen was abducted, either by a stranger, or by someone known to her. I'd consider that to be many times more likely than the "change of identity" hypothesis.
Note in November 2023 -- I am not as confident of the above paragraph now.
Continuing notes from earlier, probably around 2022....
There were various kidnappings of adults in 2021 in Sydney, generally related to organised crime. There are also, of course, cases of young women being abducted. At a glance, Kathleen does not look like someone who could fight off a powerful attacker. I think this makes her a potential target to an opportunistic abduction. We know that on her final day she was outside, walking along, vulnerable and was seen by many people. That also increases the likelihood that an opportunistic abduction could have occurred. Sydney is the abduction capital of Australia.
Abduction by a non-stranger
There is also the possibility that she was picked up by someone who knew her, or that she arranged to meet someone she knew, and that meeting ending badly. I think there is quite poor knowledge about her friends and associates in the months prior to her disappearance, so police research on this crucial avenue cannot be complete.
On this topic, it's possible she organised to meet someone wishing to purchase one of the items she advertised on Gumtree. My guess is that the detectives on the case would've explored that avenue thoroughly.
The theory that, sadly, has to be considered the most likely, is suicide. Suicide where the body is not found (or is not found within 2 years, say) can happen in the most unlikely of places. In the middle of a busy city it is less likely. But Sydney has quite an impressive harbour, and the last "official" sightings of her, she was walking toward (though several kilometres from) Sydney Harbour. Other unconfirmed sightings, and the locations where her personal belongings were found, place her in the opposite direction, but still close to bodies of water.
I found from her meetup.com account that she was a member of the "Lower North Shore Walking Group". She may have known a lot about the geography of the north shore.
Can a suicide victim remain unfound?
I wonder if there are forensic scientists or some grim category of statisticians who can comment on the likelihood of such a thing occurring.
Here are some comments from strangers, on Kathleen related threads at reddit --
A friend of mine committed suicide in 2017 by hanging himself from a tree, not even particularly high up. It was in a fairly secluded section of a public park with a lot of foot traffic. He was not found for almost eight months
Eerie reading that as something SO similar happened in my hometown! Even with a massive search, it took months. His car was even at the park, where they searched many times before locating him.
There is a well-known and astoundingly tragic case of a young man who was missing for almost ten years in Australia, and eventually his remains were located in a narrow crevice underneath or behind his own family house. No foul play was suspected in that case.
Was it a blanket?
In the photos at Bunnings she is carrying items she has presumably just purchased. One of the items looks like it could be a rope. I think it looks just as much, if not more, like a powerboard with an extension lead. Others say it could have been a blanket.
She looks sad and is carrying new blankets that come from the shop in home centre at Artarmon, clearly she was planning on sleeping with blankets somewhere.
The different items all change the probabilities on the sad question of suicide. And the blanket theory is perfectly consistent with something else I discovered: a lot of reports of bed bugs at the Elephant Backpacker hostel, Sir John Young Crescent, Woolloomooloo.
Here's an example of the Geo Targeted SMS that was sent out to the Lane Cove Area:
Social media accounts
— instagram/kate_anne_r - 458 posts. 0 followers. 66 following. This Account is Private. - "Red Riding Hood - Sydney - Seeking self-aggrandisement & validation"
— instagram/photography_kate_r - 2 posts. 0 followers. 0 following. This account is Private. Kathleen Riethmuller.
- personal facebook profile
- pinterest: katr2909 1 follower, 44 following
- linkedin: Kate Riethmuller — UQ; Data Engineer | Highly Accurate Data and Results.
- Video from panel about startups, from 2018
- Linked in account from when she was younger (before professional work but after commencement of uni) — linkedin: Kathleen Riethmuller
- dropbox — “Kat Rie”
- meetups — member of many groups in Sydney. Was “Assistant organizer” of the Sydney Users of R Forum (SURF) — a group largely coordinated by Dr Eugene Dubossarsky
- goodreads: kat riethmuller -- the nf-summaries category has lengthy book summaries, but I think these are copied (or scraped?) from elsewhere. They seem to have been added in a few batches on a small number of days.
- github: no account identified.
Kathleen placed a number of things for sale on approximately 22nd October 2021.
Example URL of one of the listings:
That is no longer online... but a copy was saved into archive.org on Nov 1, 2021 (probably by people from Websleuths)
- Archive.Org: Vintage Room divider mustard yellow 70s style | Decorative Accessories | Gumtree Australia Inner Sydney - Sydney City | 1283466595
That listing has this room divider --
Vintage Room divider mustard yellow 70s style
Good condition vintage style room divider. Some melted edging but mostly intact
And at the foot of the page it lists other things by this seller, that were listed at approximately the same time:
- Spanish mosaic framed picture
- Art canvas easel
- Lululemon yoga mat
- 7 News: NSW Police issue alert for Kathleen Riethmuller after the Lane Cove woman mysteriously vanished — Updated 31.10.2021
- facebook: nsw police - October 31 2021
- Kathleen Riethmuller | National Missing Persons Coordination Centre
- WebSleuths: Australia - Kathleen Riethmuller, 28, backpack found with personal items, Sydney, 28 Oct 2021
- reddit:r/MissingPersonsAus — Nov 1 2021
- reddit:r/UnresolvedMysteries — May 29 2022
- reddit:r/MissingPersonsAus — Aug 1 2022
- australianmissingpersonsregister: Kathleen Riethmuller
- 9 now: Missing Persons Episode 1 — aired August 14 2023.