Blonde, blue-eyed Australian Cassie Sainsbury has always stood out at the notorious El Buen Pastor prison in the Colombian capital of Bogota.

But life has changed for the former personal trainer from Adelaide after she was arrested trying to smuggle almost 6kg of cocaine out of the city's airport in April 2017.

Then 22, she had hit rock-bottom. A drug mule caught with $1.3 million-worth of cocaine, she was thrown into a tough prison in a foreign country, filled with hardened female criminals who didn't speak English.

The salacious details of her work as a Sydney escort and her money problems were dragged up in the press, and her lawyers feared she could face up to 21 years behind bars.

She looked utterly miserable.

Sainsbury at first tried to save herself with a series of desperate stories about how she was working as for an international cleaning business in Bogota, and thought the packages contained headphones that she was going to give to her bridesmaids as gifts.

She later claimed she was hired as a courier for $10,000, and that her mother and sister were threatened.

None of it worked, but a plea deal saw her sentence reduced to six years behind bars in November 2017 - potentially three with good behaviour, which was would see her released in April 2020.

The sentence could also be commuted into home-based parole in Bogota.

The judge accepted she was a "small fish" and probably used as "bait" to allow others to smuggle larger quantities of the drug out of the country.

That first Christmas was torture for Sainsbury. Fellow inmates at first held up signs through the bars reading, "Cassandra asks freedom immediately" and tried to channel the media attention into support for their own cases.

But they quickly tired of the fixation with the young South Australian and constant presence of cameras.

Sainsbury claimed she was being targeted and bullied, while the other prisoners resented the appearance of fiance Scott Broadbridge, her mother Lisa Evans and her sister Khala Sainsbury outside visitor hours.

"There is a lot of tension in the jail," one prisoner told News Corp Australia at the time. "Cassie is causing problems. She's saying that people are robbing her, extorting her and abusing her. If someone stole something at the beginning, that's normal, it's about power. But it's not happening any more and she's saying those things because she wants attention."

Former inmates scoffed at her complaints, saying foreigners were looked after by guards, and had priority with phone calls and other privileges.

Sainsbury said she struggled with the 15 other inmates with whom she shares Patio 7 - one of the better living quarters - she later told KIIS FM. "Everyone looks at white people as 'gringos'," she said. "There is a lot of discrimination. Not knowing Spanish, everything just piled on and people took advantage."

She feuded with her mother and sister, claiming they were trying to "sell her story" to the media without her permission.

Her relationship with fiance Scott was also falling apart. In the early days, he visited her in prison with an overnight bag and a single red rose. In December 2017, they announced that they were planning a prison wedding for the following spring.

But by February 2017, they had split, with Sainsbury telling the Kyle and Jackie O Show in April: "From the moment I got in here the relationship was doomed. I broke up with Scott because it was the best thing for me and the best thing for his future as well."

El Buen Pastor is Bogota's biggest women's prison, overrun with drugs, violent criminals and staffed by corrupt guards who steal food brought to inmates by their families.

Young children live with their mothers in a wing alongside "inmates who have been convicted of crimes of sexual abuse against minors", according to reports.

The prison was the subject of several media reports about filthy and dangerous conditions brought on by serious overcrowding, with bathrooms crowded and toilets blocked.

But Sainsbury appears to have learnt how to handle herself, getting on with life behind bars. After she was hit in the face while trying to break up a fight, she stopped getting involved. She put her head down, teaching English in an effort to meet the good behaviour requirements for early release.

"I keep my distance from the people I know are trying to make trouble, I'm friendly with everyone, and that's it," she said.

Last month, she revealed she had found love from inside prison, although she did not specify the gender of her new partner. "It's something that's just starting," she told New Idea.

Now 23, she's waiting to hear what life will bring for her next, and embracing life in a Bogota jail.

She's come a long way from the small community of Yorketown on the Yorke Peninsula - and she may emerge stronger for it.