An Australian academic and blogger missing in North Korea may have angered authorities in his adopted country by writing a series of "exclusive" articles for a news site run by North Korean defectors.
In another worrying development, it has emerged somebody — likely North Korean authorities — has assumed control of Alek Sigley's social media accounts in the last 24 hours.
Mr Sigley, who is originally from Perth, has not been heard from by family and friends since Tuesday morning Australian time.
Australian embassy officials in Seoul and the Department of Foreign Affairs and Trade (DFAT) are "urgently" trying to confirm South Korean media reports of Mr Sigley's arrest but admitted to news.com.au they still had no idea where he is.
The 29-year-old juggles management of a tour company bringing foreign students into North Korea for educational visits with his studies at the prestigious Kim Il Sung University, where he is taking a masters in Korean literature.
North Korea specialist Dr Leonid Petrov, a long-time friend of Mr Sigley and a lecturer at the Australian National University, said there were three main theories about what happened to him.
The first relates to authorities potentially placing Mr Sigley, a prolific blogger of all things North Korean, in lockdown ahead of US President Donald Trump's visit to South Korea for security reasons.
"There has been talk about a possible meeting between Trump and (North Korean leader) Kim Jong-un in the demilitarised zone of Panmunjom," Dr Petrov told news.com.au.
"If Alek witnessed any preparations for this on the streets of Pyongyang, it's possible they decided to play it safe and place him somewhere for security reasons because they don't want these arrangements to get out," Dr Petrov told news.com.au.
The second possibility is Mr Sigley has been involved in some kind of accident. The third and most worrying scenario involves authorities arresting him in connection with a series of stories he wrote for NK News.org, a website run by North Korean defectors.
"I think it was quite a reckless move on Alek's part to start publishing articles on the NK News platform, which is known for its hostile attitude to North Korea," Dr Petrov told news.com.au.
"It's not that the contents of his articles were critical, in fact it doesn't matter what the content was at all, it's the association with the platform, which is run by North Korean defectors.
"Alek wrote for a lot of publications and, you know, in his position you can write for The Guardian or the New York Times and it's fine, they're not going to worry about that.
"But publishing on the NK News is as bad as writing for Amnesty International. That was a mistake on his part."
Dr Petrov said Mr Sigley's most recent article was published between 10 days and two weeks ago. There are at least six other articles written by Mr Sigley since January this year but they are subscription only, meaning they were exclusive and he was likely paid for them, adding insult to injury in the eyes of North Korea.
Mr Sigley has been heavily profiled about life in the notoriously secretive country by several media organisations, including Sky News, The Guardian and Public International Radio (PRI).
Three months ago, Mr Sigley wrote an article for The Guardian in which he talked about being able to move around the capital unchaperoned and dine wherever he liked.
In February, he was featured in an article for PRI titled "Twitter and Cocoa Pops: The surprising life of a student in North Korea".
He also has a blog called From Perth to Pyongyang where he has posted dozens of articles raving about the country's food, culture and geography.
"Everything is controlled in North Korea, and so everything Alek wrote, whether it was on his blogs or social media, would have been monitored," Dr Petrov told news.com.au.
"So something has been triggered in the past few days to downgrade his status as a trusted foreigner with access to people and places others do not normally enjoy.
"It's possible he was in a traffic accident and is in hospital and doesn't want to speak with anyone, but in those circumstances it's difficult to imagine he would leave his family in the dark."
"NORTH KOREA HAS ALEK'S SOCIAL MEDIA PASSWORDS"
In a sinister twist, Mr Sigley's Facebook page has been shut down and someone has taken over his Skype account — yet his Twitter remains up and running.
"Alek's Facebook account was shut down sometime between 4pm and 6pm yesterday, and somebody is in control of his Skype," Dr Petrov told news.com.au.
"His Skype is on and someone else is using it because the green light is on yet he is not responding to messages, and I've sent him a couple.
"For this to happen it means that Alek has handed over his passwords and that is a good sign because it tells authorities that he has nothing to hide."
Asked what kind of place Mr Sigley would be held in if he was in the custody of authorities, Dr Petrov said the North Koreans had "a whole network" of guesthouses and hotel rooms just for that purpose.
"Regardless of whether his status has been downgraded or not, Mr Sigley is regarded as a friend of North Korea, so I believe his disappearance is not catastrophic but it is complicated," he said.
"North Koreans treat foreigners with respect and they have a whole network of hotel rooms and guesthouses used for holding people. The rooms, of course, are heavily monitored, and so if you say anything that concerns then the next thing is you have a security guard at your hotel room door."
Dr Petrov said if there was no word from Mr Sigley by Monday, that would be a real cause for concern.
"It's been three or four days now that nobody has heard from him, so that is a worry but it's not catastrophic — yet," he said.
"If by Monday, when the Trump visit is over, we still haven't heard from him then I think that would be very concerning."
On Thursday afternoon, Mr Sigley's family issued a statement confirming they remained unsure of his fate.
"As of 1pm (AEST), it has not been confirmed that Alek has been detained in the DPRK," it said.
"The situation is that Alek has not been in digital contact with friends and family since Tuesday morning Australian time, which is unusual for him.
"Australia's Department of Foreign Affairs and Trade is therefore seeking to confirm his whereabouts and welfare.
"Alek is an Australian-born Asian scholar and traveller who has visited, studied and lived in several countries in Asia. Alek can speak Mandarin and Korean fluently along with some Japanese.
"He is studying for a Masters in Korean literature at Kim Il Sung University in Pyongyang. Alek's family hope to re-establish contact with him soon."
A DFAT spokesman said the Australian Embassy in Seoul was trying to get to the bottom of the case.
"The embassy in South Korea is working hard to find him," a DFAT spokesman told news.com.au on Thursday.
"It has not been established positively whether or not he has been detained, but we are working very hard to clarify that."
The spokesperson said authorities had information relating to when Mr Sigley was last seen but were not releasing it for the moment.
Australia has no diplomatic mission of its own in Pyongyang and is represented in North Korea by the Swedish Embassy.
While he has undoubtedly drawn attention to himself with his prolific tweeting and blogging, Mr Sigley's observations about his adopted country are overwhelmingly positive.
He posts rave reviews about Pyongyang's restaurants, for example, and rhapsodises about the beauty of the North Korean people and their language.
His tour company is top rated on TripAdvisor and those who have left reviews say things like "a treasured experience" and "extraordinary" and "highly informative five star trips".
Executive producer for Sky News' AM Agenda, Trudy McIntosh, went on one of Mr Sigley's tours in 2013 and said she "never heard him say anything inappropriate".
"It's alarming to see this happen to him," she tweeted this morning, adding she hoped reports of his detention were "false".
On May 4 last year, Mr Sigley married his long-time Japanese girlfriend Yuka Morinaga in a wedding attended by his mother and father Gary — who is the former director of the Confucius Institute at the University of Western Australia.
He wrote about the event, which was held in Pyongyang, in his blog, saying "we weren't entirely sure what to expect, but the wedding turned out extremely well".
"A few years back our Korean business partner, a good friend of ours, suggested that if we get married we hold our ceremony in Pyongyang," he wrote.
"Years later, we made it happen … Our wedding hosted around 50 guests. We had a group of 20 family and friends join us from overseas and a group hosted by Tongil Tours.
"After the wedding day, we went on a one-week travel itinerary around the DPRK, going to Kaesong and the DMZ, sightseeing around Pyongyang and passing through Wonsan to hike in Mount Kumgang.
"Kim Il Sung University kindly allowed me to take a one-week break from classes to accompany the group. Our entourage included several honoured guests."
Among the attendees was world-renowned Russian academic and Korean history scholar Dr Andrei Lankov, who has previously taught at the Australian National University.
Mr Sigley's last social media post came three days ago and seemed innocuous enough.
Canberra advises against non-essential travel to North Korea, where several foreigners have been detained.
Consular advice recommends Australians "stay as short a time as possible, eliminate unnecessary activities and review your security arrangements".
In 2016, Otto Warmbier, a University of Virginia student, was imprisoned during a tour of the authoritarian state after being accused of taking down a propaganda poster.
Doctors said he suffered severe brain damage while in detention, fell into a coma and died days after arriving back in the United States in June 2017. He was 22.