Cassie Sainsbury's fiancee Scott Broadbridge is a person of interest to Colombian prosecutors investigating the Adelaide woman's drug case, 60 Minutes will claim tonight.
Sainsbury and her mother Lisa Evans hadn't spoken for up to five months before the 22-year-old was arrested on April 12 when police found 5.8kg of cocaine in her luggage.
Evans and Sainsbury's sister Khala, who travelled to Bogota at Channel 9's expense, claim Sainsbury doesn't fully understand her predicament.
"She tends to be up and frivolous one day and down and quite depressed the next," reporter Liam Bartlett said.
"I'm not totally convinced that the gravitas of the situation has hit home to her personally yet.
"Just the things she has said, for a person in her position, appear flippant and not grounded in reality. Her legal team tell us she is very fearful.
"This 22-year-old is facing a minimum of 21 years and four months (if found guilty) - the same amount of time she's spent on earth."
Seven's Sunday Night is also in Bogota with Broadbridge, who has suggested Sainsbury is likely to plead guilty to being a drug mule for a mystery international syndicate, despite continuing to protest her innocence.
But rival Bartlett warned the program could be in for a nasty shock about its star witness.
"We have established here, had it confirmed from the prosecutor's office, that the Colombian prosecutor now considers Scott, the fiancee, a person of interest in the investigation" Bartlett said.
"They want to interview him - sit down and ask him some questions. Over here, from what I can gather, the prosecutor's office has to rely on Scott volunteering to sit down.
"Whether or not that happens is in the lap of the gods. It hasn't happened yet. What he (Broadbridge) does or doesn't know is a very big question mark.
"I know her (Sainsbury's) legal team were very surprised to see him here.
"I asked Lisa and Khala whether or not they had suspicions about him and their answer was 'we have suspicions about a few people'.
"They refused to say no."
News Corp Australia sought comment from Broadbridge via Sunday Night, which declined to comment.
There is no suggestion that Broadbridge himself will be the subject of any charges.
The latest accusations continue the battle between Nine and Seven since Sainsbury's arrest and the ugly family feud set to play out further on air tonight.
Bartlett claimed it has taken Sainsbury's arrest to bring an end to the rift between Sainsbury and her mother which had endured for upwards of five months.
"Before she (Sainsbury) was arrested, Lisa and her daughter were not speaking," Bartlett said. "Lisa tells us it was just a normal mum and daughter argument.
"She (Evans) won't confirm if it was about Scott.
"It is clear there is deep feeling there. I know that Lisa hasn't spoken to him (Broadbridge) since she (Sainsbury) was arrested. I would have thought that is very strange.
"That is why you have been seeing this strange circus where one minute Lisa and Khala try to get into prison (to visit Sainsbury) and the next the fiance Scott tries to get in.
"The argy bargy ... comes back to a family feud thing."
"But this case is strange from start to finish. She (Sainsbury) has never been to Colombia before, she turns up, she goes from the airport straight to a hotel that is not even on the tourist strip.
"It caters for local small business people, doesn't cater for tourists, yet she goes straight there having never been to Colombia before.
"And there's no booking, no reservation.
"She pays cash - virtually on a day by day basis. And then hardly leaves the hotel. There's quite a few questions in there."