It has been claimed accused drug mule Cassandra Sainsbury worked at a second brothel in Sydney, after a number of employees came forward to detail her record of deception.

Yesterday, a major investigation by 9NEWS and 60 Minutes uncovered claims the Adelaide woman left behind a trail of deceit, even lying about her own mother’s death for financial advantage.

Following the report, 9NEWS was contacted by several other employees from a different brothel, who claim they worked with Ms Sainsbury, 22, before her Colombian trip.

"She was there a few months, similar sort of deal, fly-in, fly-out," one employee told 9NEWS on the condition of anonymity.

"That's what made us twig, it's exactly the same story that we heard about the sick mother."

Meanwhile, the fiancé of Ms Sainsbury declined to answer questions about her employment as a sex worker in Sydney just hours after he left the Colombian capital and arrived in the United States.

Scott Broadbridge was questioned by 60 Minutes after he arrived at Los Angeles airport following his trip to Bogota to see Ms Sainsbury.

Cassie Sainsbury. (Supplied)

Cassie Sainsbury pictured with the drugs she is accused of attempting to traffick out of Colombia. (Supplied)

A photo of Cassie Sainsbury taken inside prison. (9NEWS)

Mr Broadbridge remained silent before walking away.

Ms Sainsbury's mother Lisa and sister Khala have also left Bogota to return to Australia after visiting Ms Sainsbury in prison, prior to the claims airing on the Nine Network last night. They made no comment to reporters at the airport.

Ms Sainsbury is now once again alone in Colombia, with the exception of her lawyers and fellow inmates, and it could be months before her trial begins.

The bombshell revelations help to piece together missing links in the somewhat patchy back story of the young woman from Adelaide - specifically who she had been mixing with in the months before she was arrested allegedly trafficking 5.8 kilograms of cocaine at Bogota Airport.

Sainsbury and her fiance Scott Broadbridge, pictured before her arrest. (Supplied)

Sainsbury's fiance Scott Broadbridge attempts to visit her in prison. (9NEWS)

“I just feel Cassandra is not the naive sweet little blonde girl that everybody thinks she is. She's a very good liar,” one of her former colleagues told reporter Tom Steinfort, on the condition of anonymity.

That woman is one of two sex workers who have now verified that Ms Sainsbury spent the second half of 2016 working at Club 220, a brothel near Penrith in western Sydney.

Going under the working name “Claudia”, Ms Sainsbury’s internet advertisement lists her as “19 years old…classy, fun and ready to please...and in Sydney for a short time”.

The profile is accompanied by a photo of a woman in red and black lingerie – while the face is not visible, blonde hair matching Ms Sainsbury’s can be seen resting on her shoulders.

“That one there is Cassandra 100 percent. I know that outfit; I remember when she showed us she bought it. I've seen that photo, that is Cassandra 100 percent,” her former colleague said.

Ms Sainsbury claimed to be a personal trainer, but from August to December last year effectively worked as a “fly in fly out” sex worker, regularly travelling from Adelaide to Sydney for work, with her colleague telling Steinfort “sometimes she would stay for a week or sometimes just for two or three or four days”.

The details of Ms Sainsbury’s sex work have been verified by two sources in the industry, with the Nine Network also sighting documents that confirm her movements during the period.

Her colleagues said Ms Sainsbury's fiance Scott Broadbridge was aware of her sex work.

Her former colleagues have warned the public to be sceptical of the young woman, claiming she is someone that had lied to them in the past for financial advantage.

“She said her mum was suffering from MS (multiple sclerosis) and was in a private hospital in Sydney, that she didn't have private health insurance but Cassandra had done a deal with the hospital for reduced fees but she'd run up quite a debt,” her former colleague said. “Then…she had a phone call saying that her mum was dying, and then another call saying her mum had died, passed away from MS… all while she was at the brothel.”

Ms Sainsbury’s former colleagues claim a number of co-workers donated hundreds of dollars each to help Ms Sainsbury cover funeral costs, but then were astonished to see her mum was in fact alive and well on news vision emerging from Colombia over the last fortnight.

“We've been really scammed. It's not like she just mentioned it once or twice, Cassandra would go on and on about it,” her former colleague said.

“I think she's manipulative, I think she's a compulsive liar and I think she's conniving.”

Ms Sainsbury has been locked away in dingy and overcrowded El Buen Pastor prison since April 13.

The cocaine allegedly found hidden in 18 bundles in her luggage had an Australian street value of close to $2 million.

However, adding to suspicion, it has since been revealed that authorities had been closely monitoring her movements. Ms Sainsbury's unusual travel itinerary, along with a last-minute plane ticket purchased by a third party in Hong Kong, raised a red flag with authorities who tipped off their Colombian counterparts.

60 Minutes has revealed Ms Sainsbury’s lawyers’ claim that she fell victim to an international drugs syndicate, which forced her to act as a drug mule by threatening her life and the life of her family.

Colombian attorney Orlando Herron said Ms Sainsbury had got into financial strife with her gym business in Australia.

On the website Craigslist she found someone offering a loan and a trip to London – but at the last minute the itinerary was changed to Hong Kong, Los Angeles and then Bogota.

Her defence team claims she was going to back out at the last minute, but was threatened by a mystery man who showed her photos of her fiancé and family and made demands that she had no choice but to comply with.

60 Minutes revealed that while they assisted Ms Sainsbury’s mother Lisa and sister Khala with their travel to Colombia, reports in the media that the program had done a deal with the family worth $1 million are completely false.

Reporter Liam Bartlett confirmed that Lisa and Khala were unable to visit Ms Sainsbury in Colombia prior to their agreement with 60 Minutes, due to a lack of personal funds.

During filming with 60 Minutes, Lisa and Khala were finally approved a visitation with Ms Sainsbury – their first face-to-face conversation since she was charged.

She has also had separate visits from her fiancé Scott Broadbridge, who has refused to work alongside his future in-laws in their quest to save her, engaging his own lawyer.