Detectives investigating a campaign of witness intimidation during the trial of Aaron Brady for the murder of Garda Adrian Donohoe are expected to make more arrests.
The trial was the longest-running in the history of the State and continued amid an orchestrated effort to interfere with key witnesses.
Aaron Brady (29) was convicted of Detective Gda Donohoe's murder last August and is currently serving a life sentence with a minimum 40-year prison term for capital murder.
The Co Armagh man was also one of seven people arrested as part of the Garda inquiry into witness intimidation and perverting the course of justice.
The Herald has learned that detectives are expected to make more arrests as part of that investigation before submitting a file to the DPP.
Several women who made direct contact with key witnesses via social media during the trial are also the focus of the major inquiry.
Detectives are also investigating the hiring of Dublin criminals to intimidate witnesses.
Gardaí are hoping to bring a number of charges in relation to the campaign, including perverting the course of justice and using a mobile phone behind bars.
Four people with key testimony refused to come to court, but Brady was still convicted after two witnesses testified they heard him admit to shooting a garda in Ireland.
The inquiry is being led by gardaí in the National Bureau of Criminal Investigation (NBCI) with a file expected to be submitted to the DPP early next year.
Investigations into the 2013 murder of Det Gda Donohoe are also continuing with gardaí watching the movements of key suspects in the case and liaising with international colleagues.
One of the men, known as Suspect A, is a US citizen and is frequently moving between the US and Ireland.
The man's brother - who is also formally classified as a suspect - is currently appealing a serious conviction in the US.
Another man, Suspect B, was linked to a number of high-profile raids earlier this year but his crime network has been curtailed as he is now under regular garda surveillance.
While gunman Brady and four others were directly involved in the Lordship Credit Union robbery, gardaí have identified more than 20 people who were either indirectly involved or have information about the murder of Det Gda Donohoe.
In early November, Brady was arrested in his Portlaoise Prison cell and quizzed in relation to the intimidation of witnesses.
Throughout the trial, gardaí and the prosecution repeatedly raised concerns about witnesses being interfered with.
In May, during a hearing from which members of the public were banned, it emerged that a video had been leaked online of a witness giving a statement on camera to gardaí.
The video had been circulated widely on several social media platforms, branding the witness a "rat" and a "tout" while alleging they made the statement to secure a green card.
Presiding judge Mr Justice Michael White described it as the most outrageous contempt of court he had ever come across and said it was a sobering day for the administration of justice in Ireland.
Within hours, an investigation was launched by members of the Serious Crime Review Team attached to the NBCI.
Brady has appealed against his conviction for murdering Det Gda Donohoe.