Three properties in Northern Ireland have been raided and the National Crime Agency is working to establish if "organised crime groups" were involved, reported BBC.

"Detectives investigating the murder of 39 people in Grays have secured a warrant of further detention from local magistrates at Basildon for a 25-year-old man from Northern Ireland. The man, a lorry driver, has been arrested on suspicion of murder and will now remain in custody for up to an additional 24 hours, Essex Police said in a statement.

The bodies of 8 women and 31 men were discovered in the trailer of a lorry in Waterglade Industrial Park, Grays, shortly before 1.40am on Oct 23.

Deputy Chief Constable Pippa Mills said in a statement: "Our number one priority is the preserving the dignity of the 39 people who have died and ensuring that we get answers for their loved ones.”  

“We continue to ask journalists and those on social media not to speculate about the identity of the lorry driver.This is an incredibly sensitive and high-profile investigation, and we are working swiftly to gather as full a picture as possible as to how these people lost their lives," he said.