The car seat is a Cosatto brand 'Little Monster' and was in the car when it was stolen.
Garda sources have begun to fear the possibility of no-one ever being caught for the murder of Detective Garda Adrian Donohoe unless those shielding the culprits come forward.
The first arrests in relation to the fringes of the case were made on Thursday of last week - the two men, a father and son, have since been released - but fears that the possibility of no-one coming forward with hard information are growing by the week.
Yesterday afternoon, however, gardaí released pictures of a car seat and a hammer they believe the gang may have had in their possession around the time of the Kilnaleck man's brutal murder (Friday, January 25) and are appealing for information on those items (pictured), as well as repeating their appeal for people to come forward.
"I appeal to any person who has knowledge of the murder of Adrian who can help us to make contact," said Assistant Commissioner Kieran Kenny at a media briefing yesterday. "There are friends, family members of those involved, mother, father, close family members and friends of those involved who have some knowledge of this murder of Adrian. I am asking those people to contact us."
The gang of five thought responsible contain three south Armagh siblings - the teenage female getaway driver and her two brothers and two men also in their early 20s. The Anglo-Celt understands that one of those two [pictured] is the chief suspect to have pulled the trigger and is on the run in Scotland but all members are thought to have provided investigators with alibis for the night Garda Donohoe was murdered. The chief suspect is also thought to have links to a leading Ulster GAA club.
He is believed to be on bail in relation to serious charges in the North and is thought to be the boyfriend of the teenage girl, while the remaining gang member is thought to still be in the Republic.
Gardaí say they have carried out 800 interviews and followed 2,300 lines of enquiry so far in the case and it is understood 140 pieces of CCTV have been reviewed relating to the murder which shocked the country on the night of Friday, January 25, at Lordship Credit Union in Co Louth - just a mile from where he lived.
The unthinkable possibility of not bringing the culprits to justice, sources say, could come about due to a lack of new evidence or witnesses, the 'alibis' provided, those with information refusing to come forward and the amount of time it will take to bring the case.
An Garda Síochána have added 50,000 to the 50,000 reward already on offer from the Irish League of Credit Unions for information.
However, last week, the additional gardaí who were drafted into Dundalk were reported as returning to duties at other stations.
"There is the possibility that no-one will ever be caught," a well-placed source said.
"The problem is that for those closest to the investigation they have a very good idea who it is - it's a case of building evidence and an air-tight case but that fear has entered the frame and the family are aware of it."