"I don't think she was naive." Cassie Sainsbury's uncle isn't buying her story.

Cassie Sainsbury’s uncle, Neil Sainsbury, believes the 22-year-old knew what she was doing when she planned to fly out of Colombia carrying 5.8 kilograms of cocaine last month.

“Cassie has a bit of a history of skipping from one place to the next when things get a bit tough. I don’t think that she was naive at all,” Neil Sainsbury told Channel Seven’s Sunday Night.

“She had knowledge of what she was doing. Perhaps she may have had complete knowledge.”

Cassie told authorities she bought the packages off a tour guide, thinking they contained headphones that she was planning to give to the bridal party in her upcoming wedding.

Her bags were searched in Bogota airport and Cassie was arrested on charges of drug trafficking. If found guilty, the Adelaide woman will face up to 25 years in Colombian prison.

ON NOW: Cassie’s uncle, Neil Sainsbury, denies her claims he sold his business to a mystery couple who sent her overseas. #SN7 pic.twitter.com/Er8GUcnAtI

— sunday night (@sundaynighton7) May 21, 2017

Her fiance, Scott Broadbridge, believes she was set up.

He said Cassy received payments from the owners of a cleaning company – Karen and June Dolshol. He alleges the pair bought the cleaning company off Cassie’s uncle, Neil, and then used her as an unknowing drug mule.

"I don't know if the business she worked for set her up, or if it straight from Colombia," he told Sunday Night.

"But I believe she was set up as a drug mule without her knowledge."

Neil "categorically denies" Scott's claims, saying he's never owned a cleaning business, "I've never owned any business whatsoever," he said.

On #SN7 now: Cassie’s father, Stuart Sainsbury, records a message for his daughter. pic.twitter.com/fY907IFtgW

— sunday night (@sundaynighton7) May 21, 2017

Cassie's father tells a different story again.

He refused to comment on his daughter's guilt or innocence. "I can't sit here and lie. There are just 68 different stories," he sad.

But revealed his daughter had been planning a trip to Colombia since January this year - a story very different to Cassie's own claim that it was a spontaneous decision.

He didn't want her going to Colombia from the start, because of the danger it would all-too-likely involve.

"It was as simple as; 'don't be stupid'," he told Sunday Night.

Why are we so obsessed with Cassie Sainsbury's story? Post continues.

"I had a big blow-up with Cassie over that but, when I saw her again after that, she said 'we're not going, Dad' and I said 'okay, thank you'."

He hasn't heard from his daughter since her arrest but, talking to Sunday Night, he recorded a message he hopes reaches her.

"I don't know what the hell's going on, Cass. I haven't heard from you. Just remember I always love you and you know where I am," he told the cameras.

This comes at the same time as claims Cassie was employed as a fly-in fly-out sex worker in Sydney during six months of last year, and that the 22-year-old was reportedly "threatened" before going to the airport in Colombia.