The officers told her she needed to leave her home in a gated community on the outskirts of Guangzhou and accompany them immediately to the local police station to help them with their inquiries. Chou left her son, sound asleep and in the care of his nanny, oblivious to the fact that it would be the last time she would see him for  6½ years.

What would unfold is a remarkable account of being lost in China's labyrinthine judicial system and harsh prison environment. It is also a cautionary tale of the risks of doing business in China.

After being taken to the local police station, Chou was locked in a cramped interrogation room furnished only with a broken wooden table and stool. Two men took turns to keep watch, their sole job to prevent her from falling asleep. She was kept awake for four nights, interrogated, and denied access to a lawyer, family or Australian consular officials.

Constantly willing herself not to break down, Chou says the music and images of a slideshow she had recently made of Lincoln's first birthday kept flooding her mind.

"All I could see was [my] baby's face appearing in front of me," Chou, now 50, told Fairfax Media in her first interview since her release from jail last Saturday. "I sang along with the song."

Eventually the station chief told her she had been reported for bribing a tax officer, by none other than her business partner and long-time backer, Hong Kong businessman Zhu Hanbang, who also goes by his English name, Tony Chu.

Playing good cop, the chief assured her that the offence was minor and that she would be released swiftly if she co-operated. All she needed to do was to sign a confession. Physically and mentally exhausted, she acquiesced. Finally, she was allowed to sleep.

"It was the best sleep of my life," she said of the night spent on a fold-out table, with a police coat as her blanket.

When the Australian consulate was notified of Chou's detention, it was three days later than required by consular agreement. When Australian officials met with Chou, police insisted her case could not be discussed because they involved "state secrets". The same reason was given to prevent her access to  a lawyer for six weeks.

Zhu would later concede to Fairfax Media that the bribery he reported related to his own tax affairs and that if any bribes were paid, it would have mostly been with his money. But police at the time took no interest in his involvement. "Every time Charlotte said pay this ... I just gave money to her and I really don't care who she paid," he said in a 2011 interview. 

Tried and convicted on the basis of her sleep-deprived confessions, Chou was sentenced to 18 months in jail.

Released on December 28, 2009, she was immediately re-arrested at the prison gates in front of her family and friends who had gathered to greet her, their elation swiftly giving way to anguish as it dawned on them what was transpiring.

"We were just standing outside waiting and chatting excitedly," her younger sister, Fiona Zou, recalled. "[Then] two policemen came out of their waiting car and took her away."

Before being taken back into detention, Chou pleaded for one phone call to her son Lincoln, who had moved to live with his grandmother in Sydney. A faint cry of "Mummy" was the first time she heard Lincoln speak.

"I've cried many times thinking of this scene," Chou says. "I had no words. I didn't know what to say." It would be another five years before Chou would walk free again.

The cruel twist haunts Chou and her family to this day. It motivated their request for this interview not to be published until Chou had left mainland China safely.

Chou arrived home in Sydney on Wednesday morning to an emotional reunion with her elderly parents and Lincoln, who greeted her at the airport with two "welcome home" balloons and a long hug.  Chou was again left lost for words, this time out of sheer joy. "It was so emotional, my mind went completely blank," she said.

Bitter feud

At best, Chou's case was dotted with procedural delays, irregularities and apparent tendency to ignore seemingly straightforward evidence in her favour. At worst, as Chou's supporters contend, it was a spiteful case of judicial bribery perpetrated by her Hong Kong backer Zhu in order to wrest control of the lucrative private university she had created.

Chou had built the university, the South China Institute of Software Engineering, with Lin Yongping, a mainland Chinese business man, who Chou later became personally involved with. Chou was divorced from the father of her two older children and Lin is the father of third and youngest child, Lincoln.

Zhu, a Hong Kong itizen with powerful mainland connections, says he helped Chou secure a lucrative job (something Chou herself denies) managing the finances of the Chinese investments of an American billionaire. When plans to build an American theme park on land in Guangzhou in failed to materialise, Chou brought in Lin to invest in the redundant land which later became the site for the university.

But Chou says Zhu came to despise Lin, something Zhu tried little to disguise in his 2011 interview with Fairfax Media. "I don't know how she fell into such a mess with a man from China," Zhu said at the time. "Charlotte is also a victim. I have great sympathy for the family, the only thing I can say is I'm sorry.

"It's not because of the romantic relationship, they hid accounts from us," he says. "I did think 'something is cooking you know, something'. As a result I sued everybody."

Lin fled mainland China after Chou's initial arrest. He has had little contact with her or their son since.

Zhu, a mere 5 per cent shareholder, would eventually  seize control and sell the university, which had grown to more than 10,000 students and was worth, by conservative estimates, more than $1 billion.

The second time Chou was taken into detention, she was charged with embezzlement in relation to a catering contract to the same tax official she was convicted of bribing.A year later her lawyer was finally shown a trolley full of evidence against her – at lunch time on the first day of her trial. Another embezzlement charge was added two years after the trial first began, revolving around a 29 million yuan ($5.7 million) amount prosecutors said was illegally siphoned from the university.

After repeated delays and seven court appearances during nearly 30 months in detention, Chou was sentenced to eight years jail.

This was later reduced by three years after a re-trial: prosecutors accepted that the latter embezzlement charge was actually a repayment of a clearly documented loan.

In a separate development, with Zhu in Hong Kong, two of his financial staff at the university were arrested by Guangzhou police in May.

Crammed into cell

Chou's lengthy court process without verdict meant she wound up serving her entire time behind bars in two detention centres, rather than being transferred to a permanent prison.

She was crammed into a cell with 15 other detainees, her bed a cement platform raised 15 centimetres  the ground. Every night, two to three detainees were ordered to take rotating two-hour shifts, keeping watch at night to prevent suicide attempts or violent attacks.

Time constraints meant two inmates had to share a shower, cleaning themselves with the same bucket of water. The days were spent on manual prison labour, assembling plastic flowers, packing boxes of plastic gloves, and sticking trinkets on Christmas cards. Evenings were spent sitting silently in formation for five hours in front of a television perennially tuned to state broadcaster CCTV.

Contrary to prison regulations, there was no outdoor activity.

"Once I was taken to a meeting room and I noticed a tree outside a window and I was so excited," Chou says. "But immediately I was ordered not to look."

But for Chou, the hardest thing about being in jail hadn't been the harsh conditions, the frustrations of China's labyrinthine judicial system, nor the knowledge that the ownership of the private university she had worked obsessively for years to establish was being wrested away by a rival business partner.

It wasn't the shock of being taken without warning from her home in the middle of the night, while her 1-year-old son was sound asleep; being tried and convicted based on a sleep-deprived confession, or even the scarring experience of being released from jail after serving an initial sentence, only to be immediately re-arrested at the prison gate in front of stunned family and friends.

Quite simply, she says, it was the personal toll of being away from her family – particularly Chloe and Cleon, her two teenage children, and Lincoln.

Chou saw her two older children only once each during her time in jail when they travelled to attend one of her hearings in Guangzhou during her trial. "If she didn't call out, I wouldn't even have recognised her," Chou says of Chloe, now a 21-year-old who graduates from her event management degree in Sydney next year. Similarly, she was shocked to see her son, Cleon, now 19 and studying information technology at a university in Beijing, had shot up to more than six feet tall.

Chou refuses to be bitter about her time spent in jail, saying it has made her more determined to spend her time positively as a free woman. "I've lost a lot in that period but frankly speaking ... my family lost more," she says. "My kids were without their mum, my parents without their daughter."

Chou plans to petition to have her verdict overturned, but says it is more about obtaining justice rather than trying to win the university back, which she considers a distant proposition.

She also wants to use her personal story to send a message: that for all the opportunities it presents, doing business in China comes with its fair share of risks that need to be understood.

"Don't think it's so far-fetched and it can't happen to you, the detention centre is not that far away," she says. "It could be the political risks or the legal environment, you can't see this in business or legal manuals."

There are also plans for a book, to be penned in Chinese, based on the back stories of people she met  while in detention, from alleged drug traffickers to murderers.

Chou promises her work will not be an "autobiography on how miserable her life in prison was", though her own experiences did provide the inspiration for one of the main characters' names – Yuan Wan'er, a rough homonym for being "innocent and completely wronged".