Gardaí have renewed their appeal for information after five letter bombs were posted from Ireland in March.
Three were delivered in London, one was delivered in Glasgow, while the fifth parcel was returned to the Limerick Postal Centre.
On March 11, a group calling themselves the ‘New IRA’ claimed responsibility for the packages.
"This extremely dangerous and reckless act endangered the lives of innocent persons and could have caused serious harm to anyone handling these devices," a Garda spokesperson said.
Gardaí want to eliminate anyone who may have innocently come into contact with the letters bombs and to identify anyone - postal workers or other persons - in Ireland who may remember collecting or seeing the parcels around March 1 from postal delivery locations within Ireland.
Anyone who remembers seeing the parcels or who has any information is asked to contact the Garda Síochána Confidential Number 1800 666 111, or the Crimestoppers Number 1800 25 00 25.
The London Metropolitan Police have also issued an appeal which said the investigation teams have linked the packages to those sent to various British Army Recruitment Centres in 2014.
"Our enquiries continue, but clearly a key element of the investigation now is the link between the devices previously sent in 2014, and the five sent earlier this year," said Deputy Assistant Commissioner Dean Haydon from the UK’s Counter-Terrorism Policing.
"As with any investigation, we will be led by the evidence, but at this stage, our principal line of enquiry is that the devices were sent by a violent dissident republican group."