Four men suspected of playing central roles in the kidnap and robbery in Co Dublin last week in which over €500,000 was taken were due to be released by gardaí early this morning.
The men, who are among 13 people arrested in the investigation so far, were due for release at 1am from a number of Garda stations in Dublin.
Senior Garda sources said deliberations would continue with the DPP's office until the 1am release time on the possibility of charging the four men immediately and bringing them before the courts as early as today.
However, the same sources said, given the time-consuming nature of the Garda inquiry, it was more likely the men would be released and that charges would be brought in the near future.
"We've identified a number of scenes and vehicles used and obviously any forensic evidence we get that links the suspects to the crime will be crucial. But that kind of evidence takes a long time to process," said one reliable source.
The four men were arrested at a hotel in Ballymun at 1am on Friday morning following Thursday's robbery. Two of them are leading gangland figures, who have had addresses in Cavan and Balbriggan, Co Dublin, of late.
Two are aged 41, while the others are aged 30 and 27. They are among 13 people who have been arrested by gardaí since the robbery of the Bank of Ireland in Balbriggan.
The first two people arrested, an 18-year-old woman and 23-year-old man, were detained after gardaí stopped a car in Julianstown, Co Meath, at around midday on Thursday.
These two were last night the only two of the 13 suspects to have been released.
Gardaí wrongly believed the car they were travelling in contained the €500,000 withdrawn by assistant bank manager Gerry Smith for the safe return of his kidnapped wife, Margaret, and sons Killian (23) and Conor (17).
However, when the car was stopped, a search for the money yielded nothing. gardaí now believe the cash dropped off by Mr Smith at the Malahide estuary was taken away in another vehicle.
After the arrest of the couple the four key suspects were arrested at 1am on Friday. Later that day a 20-year-old man was arrested in the Edenmore area of north Dublin. He is a brother of one of the four men arrested at the hotel.
Two women linked to two of the four main suspects were also arrested in Balbriggan on Friday. And late on Friday night two men were arrested in Finglas in connection with the kidnap robbery.
Garda sources said, along with the four men arrested in the hotel, the two detained in Finglas are suspected of having played very significant roles in carrying out the kidnap robbery.
These two men were last night being held at Santry and Whitehall Garda stations.
A further two men were arrested in Bailieboro, Co Cavan, on Saturday night.
Three cars used in the attack have now been recovered. The third of the vehicles, a green Ford Focus hatchback, was located in Slane, Co Meath, following a Garda appeal late on Saturday night.
All three vehicles were being technically examined over the weekend.
A mobile home in Moynalty, Co Meath, where Mrs Smith and her sons were held in the early hours of last Thursday morning, has also undergone a major technical examination, as has the Smith's family home in Castlefarm, Swords.
It was there that the family's ordeal began when four armed and masked men called to the house at 8.30pm last Wednesday.
While the four main suspects were due to be released or charged by 1am this morning, the other seven suspects still in custody last night are due for release or charge over the next two days.
All of the arrests were carried out under Section 30 of the Offences Against the State Act, allowing the detention of the suspects for up to 72 hours without charge.