The location in Essex where the tragic find was discovered.Gardaí are trying to find if travelled through Dublin Port before arriving in Holyhead.
Gardaí say they are investigating if the container in which 39 people were found dead in Essex travelled through Ireland.
They're trying to establish if it came from Bulgaria, on to France, through Rosslare and onto Dublin Port before arriving in Holyhead.
A 25-year-old man from Northern Ireland has been arrested on suspicion of murder after the discovery of the bodies of 38 adults and a teenager.
Essex Police say they were called to the scene at Waterglade Industrial Park, Eastern Avenue, Grays by the ambulance service at 1.40 am this morning.
''This is a tragic incident where a large number of people have lost their lives. Our enquiries are ongoing to establish what has happened,'' Chief Superintendent Andrew Mariner said this morning.
''We are in the process of identifying the victims, however I anticipate that this could be a lengthy process. We believe the lorry is from Bulgaria and entered the country at Holyhead on Saturday 19 October and we are working closely with our partners to investigate.''
''We have arrested the lorry driver in connection with the incident who remains in police custody as our enquiries continue,'' Mariner added.
"If the lorry came from Bulgaria, getting into Britain via Holyhead is an unorthodox route.''
Seamus Leheny, Northern Ireland policy manager for the Freight Transport Association (FTA), said it is believed the lorry would have entered Holyhead from Dublin.
He said: "If the lorry came from Bulgaria, getting into Britain via Holyhead is an unorthodox route.
"People have been saying that security and checks have been increased at places like Dover and Calais, so it might be seen as an easier way to get in by going from Cherbourg or Roscoff, over to Rosslare, then up the road to Dublin."
Taoiseach Leo Varadkar today told the Dail that the deaths were a "tragedy" and promised to carry out an investigation if "necessary".
He said: "The information that we have so far this morning is very sketchy, but there are some reports that the truck may have passed through Ireland at some point so obviously we're going to need to get more information and carry out any necessary investigations which may be required."
