The Peruvian prosecution lawyer building the preliminary case against Dungannon alleged drugs mule Michaella McCollum says he doesn't believe a word of her story.
Dr Juan Mendoza Abarca, head of the state attorney's office anti-drugs unit, has dismissed Michaella and her Scottish friend Melissa Reid's "very well practised" versions of events.
The 20-year-old women – known as the Peru Two – are accused of attempting to smuggle 11kg of cocaine, worth more than £1.5m, out of the South American country.
The pair face at least two years in the tough Virgen de Fatima prison while they await trial, and could face 15 years in jail if found guilty.
In an interview with the Mail on Sunday, Dr Mendoza Abarca said the women's excuses were "very well practised", they had been coached in what to say and their "demeanour did not suggest that they had been threatened".
Dr Mendoza Abarca said: "They don't even have one element of proof.
"Unfortunately, their stories are not believable – their stories are incredible. They staged this whole thing from the beginning because they knew it was possible they would get caught and if they did get caught they had the excuses really well planned.
"The problem is that they received the drugs, they packed the drugs in their bags and they went to the airport. But had they been given the bags packed already –which is what usually happens –then it's another story.
"When somebody is threatened, you can tell. I have spoken to the girls and their demeanour did not suggest that they had been threatened because of the way they acted.
"They were told to take pictures of themselves having a good time, to try to act as normal as possible. All of the excuses were very well practised."
The case is now in the hands of the judiciary, but Dr Mendoza Abarca has been privy to all the evidence in the first 15 days of the case.
He believes Michaella and Melissa will end up pleading guilty to secure a minimum sentence.
The only two foreigners in the Vigen de Fatima prison, they are said to dislike the food available to them and have gone into 'survival mode' to cope with their new lives.
STORY SO FAR
The haul was hidden in their luggage at Lima's international airport. They claim they were coerced into carrying the drugs. If found guilty they could face 15 years in a Peruvian jail.