Police are continuing to question four suspects over the deaths of 39 people whose bodies were found inside a lorry in Essex.
A man was detained at Stansted Airport on Friday on suspicion of manslaughter and conspiracy to traffic people.
Two people, a man and a woman, both aged 38, from Warrington were also held on the same charges, while the lorry driver has been held on suspicion of murder since Wednesday.
The arrests came as efforts to remove and identify those who died continued.
Police officers have been seen at the home address of the arrested couple, a man and a woman, who are both 38.
The man arrested at Stansted Airport is aged 48 and is from Northern Ireland.
Police have been given extra time to question the 25-year-old lorry driver, Mo Robinson, of County Armagh.