Belgian authorities are investigating the journey of a lorry container where 39 people were found dead in Essex, focusing on who organised the transportation.
Preliminary results show the container arrived at Zeebrugge on Tuesday afternoon before travelling to Essex, where it arrived at 1am.
The bodies - including one of a teenager - were discovered shortly after.
A 25-year-old man, named locally as Mo Robinson from Portadown in Co Armagh, Northern Ireland, is being held on suspicion of murder over the discovery.
The latest details come as a friend of the family said Mr Robinson’s father learned of his arrest through social media.
According to Sky News, the Belgian public prosecutor's office said it is "not yet clear" when and where the victims were placed in the container, adding that no further information would be released at this time.
Their investigation found the container arrived at Zeebrugge on Tuesday afternoon at 2.49pm local time and left the port the same day.
It then arrived in Purfleet at around midnight. CCTV has shown it being driven towards the industrial park where the discovery was made in Grays at 1.10am, half an hour before Essex Police were called to the scene.
The statement said authorities in Belgium would continue to work with police in the UK to find out what happened.
Eric Van Duyse, a spokesman for the prosecutor's office, said it is not clear how long the lorry spent in Belgium.
He said: "We have no idea at the moment how long the lorry spent in Belgium, it could be hours or days, we just don't know."
Meanwhile, police have raided two addresses in County Armagh that are believed to be linked to the driver.
Local councillor Paul Berry said the village of Laurelvale, where the Robinson family live, was in "complete shock".
Mr Berry, who has been in contact with Mr Robinson's father several times, said he learned of his son's arrest through social media.
"He had said he had been getting messages via people on social media on what was happening and at that stage it was not confirmed to him or his family that his son had been arrested," said the independent representative.
"In the local area the feeling is one of complete shock and hope this is not a true story in terms of his involvement."
Mr Berry said the family was "very well respected" in the area.
"The local community is hoping that he (Mo Robinson) has been caught up innocently in this matter but that's in the hands of Essex Police, and we will leave it in their professional hands to try to catch the perpetrators of this."
He said the family had been left upset by the "unwelcome spotlight" the incident had shone on them.
"It was very distressing for the family as they just felt they were captive in their own home," he said.
Mo Robinson was arrested after the discovery at Waterglade Industrial Park. He had been driving the lorry before police were called to the scene.
Speaking on Wednesday afternoon, Deputy Chief Constable Pippa Mills said the lorry and the container were being moved to nearby Tilbury Docks so the bodies can be recovered while preserving the dignity of the victims.
"We are yet to identify them and must manage this sensitively with their families," she added.
The incident follows warnings from the National Crime Agency (NCA) and the Border Force of the increased risk of people-smuggling via Belgium.
An NCA assessment report on serious and organised crime last year said there was a "greater focus" on rising smuggler numbers in Belgium after the closure of the Dunkirk migrant camp in 2017.
