Irish army personnel based near the border at the time two senior RUC officers were murdered by the IRA are expected to be interviewed by the Smithwick Tribunal.
Officers will be asked to verify reports that some gardai were ordered to stay away from border military barracks because they were considered security risks.
It's understood that one former Irish army officer has made a statement to the tribunal in which he claims that at least one Garda based at Dundalk in the 1980s was told that he was not welcome to visit barracks along the border.
The evidence is expected to open up a new avenue of investigation into the ambushing of Chief Superintendent Harry Breen and Superintendent Bob Buchanan near Jonesborough shortly after they had left Dundalk Garda station in March 1989. The tribunal has already heard that both Breen and Buchanan had separately expressed concerns about the presence of one particular officer based in Dundalk at the time they were murdered.
This week, tribunal lawyers will travel to England to speak to a British Army officer who has agreed to answer questions about the handling of informants recruited by the intelligence gathering Force Research Unit. The FRU handled one of the most highly placed informants inside the IRA, west Belfast republican Freddie Scappaticci, who used the pseudonym 'Stakeknife'.
Scappaticci is believed to have liaised with rogue gardai along the border who provided information to the IRA.
Last week retired Garda Superintendent Tom Curran told the Tribunal that during a meeting in 1988 Buchanan told him that Garda Detective Sergeant Owen Corrigan was "unnecessarily associating" with IRA activists.
He said he "got the impression that he (Corrigan) was assisting the IRA" as a result of the conversation and arranged to meet the then Garda Assistant Commissioner Eugene Crowley in Dublin to tell him of Buchanan's concerns.
Mr Curran said he was never contacted about Buchanan's concerns following the conversation with Crowley who died in 2009.
Owen Corrigan has dismissed the allegations made against him as a "monstrous lie".