"She mentioned about these headphones that she wanted to get and this man said to her, 'Well I know a guy that if you buy 16 or 18 of them he can give you a really good price'," Evans said.
"He had been helping her all week, taking her around and showing her places and just being a nice guy. Then when he said this Cassie said, 'oh, OK'.
"Then the day of her departure he came up to her hotel, gave her a package that was wrapped in black plastic we think, and she took it, put it in her luggage and this is where the naive bit comes in, she didn't even rip it open to make sure there was just headphones in there.
"Whether he was just using her as bait and there was another big shipment trying to go through ... so she would get caught, I just don't know."
Sainsbury is being held at the El Buen Pastor jail, notorious for its overcrowding and annual beauty pageants. She last spoke to her mother about a week ago and said she was safe and learning Spanish.
Her family has raised more than A$2200 ($2400) via the online FundRazr website and hopes to get A$15,000 to cover her legal bills.
Evans, who is on a disability pension, says her daughter has a good lawyer who says if she pleads guilty she faces a minimum sentence of six years compared to 18 to 25 years if she pleads innocent and is found guilty.
But she fears her daughter has little hope of tracking down the man who helped her buy the headphones.
The Department of Foreign Affairs and Trade says it is providing assistance to an Australian woman arrested in Colombia but offered no further details due to privacy.
- AAP
