DRUG mules Michaella McCollum and Melissa Reid are likely to face a six-month investigation if their guilty pleas are not accepted, the Peruvian prosecutor in charge of their case has said.
Juan Mendoza made the comments after the women, both 20, made a second appearance before a judge at Sarita Colonia del Callao jail, in Callao, near Lima. He did not give details of the private hearing but suggested the women's confessions had not yet satisfied prosecutors.
However, it is thought that if they are to remain in Peru, the two women may be moved to a low-security prison.
Last week McCollum, from Dungannon, Co Tyrone, and co-accused Reid, from Glasgow, pleaded guilty to drug smuggling. They had hoped the behind-closed-doors admission would be enough to secure a shorter sentence.
But prosecutors have demanded more information before accepting their admissions of guilt which the women hope will bring their jail time down to six years and eight months.
Mr Mendoza, speaking to The Associated Press, would not discuss whether the women had explained to them how they got the cocaine, or who it was from.
McCollum and Reid initially claimed they were kidnapped, held at gunpoint and forced to board a flight from Lima to Spain with 24lb of cocaine in food packets hidden inside their luggage when they were arrested.
However, Mr Mendoza has indicated prosecutors remains unconvinced by the two women's claim about being forced to carry €1.7m worth of cocaine by a drugs gang.
It means that suggestions that the pair could be repatriated to serve their sentences at home by Christmas seem optimistic.
The pair were last night hauled back to a makeshift courtroom in a men's prison in Lima to face more questions about the gang that allegedly sent them to Peru to pick up the drugs.
Melissa, from Dungannon, Co Tyrone and Melissa, from Lenzie near Edinburgh were asked to expand on statements they made last week in court after confessing to trying to smuggle the drugs back to Europe.
Prosecutors had refused to agree to a deal giving them a shorter prison sentence unless they gave them more information about the drugs trafficking gang and admitted they were not forced to Peru at gunpoint.
The women, both 20, insist they were coerced into smuggling drugs for fear of their lives by Colombians they met in Ibiza where they were working over the summer.
Under Peruvian law the deal they were hoping to strike is called an early termination process and would mean they would automatically receive a six-year eight month jail sentence, an eighth off the minimum sentence for drugs trafficking of eight years.
A spokesman for Callao Criminal Court number four which is investigating the women, confirmed last night the pair had appeared in a private hearing before a judge.
The spokesman said: "This morning, in one of the rooms of Sarita Colonia men's prison, Michaella McCollum and Melissa Reid amplified their statements.
"The hearing in front of judge Pedro Miguel Puente Bardales took place because on September 25 state prosecutors asked in writing that before the early termination hearing which had originally been scheduled for yesterday the defendants expand on their court statements.
"The court arranged for that to happen.
"A week ago both women had accepted their guilt for the crimes they were accused of, showing their repentance and asking at the same time to be accepted within the early termination process.
"Today's hearing was private."
It was not clear last night what the women said during the hearing.
It is thought prosecutors will now take time to review the women's expanded statements before deciding if they are ready to strike a deal.
If they still feel the women are holding back information, they will force them to go to trial where they could face up to 15 years in jail if found guilty.
As part of their carrot and stick approach, they have also hinted they could be free by Christmas if they agree to collaborate in bringing to justice the drugs gang that sent them to Peru.
Meanwhile, it is thought that the women may be transferred to Ancón 2, a modern low security prison located about one hour north of Lima. Most foreign female prisoners are currently being held in Ancón 2, which is considered a model prison for low security prisoners. It currently has 1600 prisoners.
The prison has 14 sociologists, 6 lawyers, 6 nurses and a nutritionist.
Inmates have the opportunity to study pre and postgraduate university courses as well as learn technical skills in workshops such as hairdressing, beauty therapy and handicraft.
Speaking before yesterday's hearing, chief state prosecutor Juan Mendoza Abarca said: "What the girls have said so far is not enough.
"We want to get to the men behind them and we want more information off them to do that.
"It's not enough to say you've killed someone and not say how or why.
"All these girls have said is 'We're guilty' and very little else.
"They've given a four-line statement to the court which doesn't help us track down the gang that sent them to Peru in the first place.
"For the women to benefit from the early termination procedure and receive a reduced prison sentence, all sides including state prosecutors have to be in agreement.
"As things stand at the moment with the information the women have given the court, we don't agree to them benefitting from the early termination process."
Melissa and Michaella returned to their remand prison after the hearing.