In a paid television interview, Jodie Power claimed she wanted to set the record straight about what she had witnessed as Schapelle's sister Mercedes's close friend for 14 years, until a falling-out with the family last year.
Ms Power, who passed one lie-detector test after failing an initial test over her claims made to the Seven Network's Today Tonight program, made a litany of serious unsubstantiated allegations involving drugs against Mercedes and Corby's father, Michael.
An angry and emotional Mercedes Corby last night hit back at Ms Power's claims, describing her former "difficult" friend as "unstable, delusional and greedy".
"It's all lies. Just a whole lot of lies," she told The Australian.
"I cannot believe she's stooped so low. She's on a vendetta. She's vindictive, manipulative and a liar. She's got mental problems and she'd do anything for money.
"I'm prepared to take a lie-detector test, anything, against all of this stuff."
Ms Power's claims come after The Australian's May 2005 report on the Corby family's alleged history with drugs, including Michael Corby's minor drug conviction in the 1970s, and later revelations that 5kg of cannabis was seized from a property next door to Michael Corby just one month before Schapelle's arrest.
Ms Power had previously steadfastly defended Schapelle's innocence and sat next to Mercedes during the court case in Bali when her sister was sentenced to 20 years in jail for smuggling 4.1kg of marijuana into Bali. Ms Power flew to Bali the same day as Schapelle - October 8, 2004 - and spent the next few weeks visiting her in prison.
Asked why she had not told authorities of what she knew, she said it was because she feared that Schapelle would face the death penalty. "I didn't want her to be shot and Mercedes has just lied so much that she's tried to manipulate everyone," she said.
Ms Power said that growing up with Mercedes, she had often seen marijuana at the Corby house. "I know when I was 19, 20 I wasn't allowed to have a beer at her house but I was allowed to smoke a joint," she told the program.
She claimed Mercedes had told her she had taken small quantities of marijuana into Bali prior to Schapelle's arrest and had allegedly asked her if she would ever take marijuana overseas.
"She just asked if I would ever do it, if I would ever take drugs over and I said no, like I've got two kids and I wouldn't do that and she went on to tell me that she had actually taken them over before.
Mercedes admitted she had smoked marijuana in her youth but said Ms Power's claims about her involvement with drugs were "nonsense".
"Look, I've got three children and I don't take drugs. Those pictures (in the Today Tonight report) were from when I was 17 years old. I've never been a heavy smoker, I've never been a pothead. Everybody knows that - Jodie knows it. I've had a few puffs, that's all.
"As for me taking marijuana to Bali, that's rubbish. I shouldn't have to be defending myself against that nonsense.
"Jodie's always been my 'difficult' friend, but I've always been there for her, until finally, I said a while ago I couldn't be there any more.
"She helped out in the first month after Schapelle's arrest but then she went home to Australia and came back, and she was a different person.
"She started a fund, she was asking people for money, we wanted to get Dad to be able to come over here and so on.
"I started asking her for some of the money and all she could come up with was excuses. She had a hangover, she couldn't find her passport, she couldn't get to the bank to get the money out - stuff like that.
"Finally Mum said we're just going to have to sue her for the money, and that's when she started getting really nasty." She said she had not spoken to Ms Power since July 2005.
Ms Power also claimed to have seen marijuana in vacuum-sealed bags at the Corby home similar to the bag containing drugs that was discovered inside Schapelle's bodyboard bag.
Last year, it was revealed Mr Corby - who was convicted for possession of a small amount of marijuana in the 1970s - was a former workmate and twice a neighbour of Anthony Robert Lewis, 57. Mr Lewis was charged with setting up a hydroponic marijuana plantation on his property near Iveragh in Queensland, next door to a property owned by Mr Corby.
Police seized 5kg of cannabis in a vacuum-sealed bag at the Lewis property, a month before Schapelle Corby was arrested in Bali. Mr Corby was never accused by police of growing drugs.
Ms Power claimed Mercedes had once asked her to go to her father's property to water plants.
Asked what sort of plants, Ms Power said she was told they were "marijuana plants".