Efforts to identify 39 bodies found inside a lorry are focusing on the Vietnamese community, police have said, as officers seek to establish whether a “wider conspiracy” was involved.
Eight women and 31 men were discovered in Grays, Essex, on Wednesday.
Det Ch Insp Martin Pasmore said he remained “open-minded” about the nationalities of the victims.
A fifth person has been arrested in connection with the deaths, while four suspects remain in custody.
The victims – whom police initially believed to be Chinese nationals – were inside a refrigerated trailer which came to the UK via the port of Zeebrugge.
Essex Police said there had been a “large amount of engagement” from the Vietnamese population since the discovery.
VietHome, an organisation that represents the Vietnamese community in the UK, said it had received photos of nearly 20 people reported missing.
In Vietnam, Father Anthony Dang Huu Nam said he had been told of “more than 100” people who left the Yen Thanh province “on their way to a new life”.
Families from the area believed their relatives were victims of the “tragic journey”, he said.
Det Ch Insp Pasmore, who is leading the Essex force’s identification efforts, said the bodies had been removed from the trailer and taken to Broomfield Hospital in Chelmsford.
Those inside were carrying “very few” identity documents, leaving officers to rely on fingerprints, DNA and distinguishing features such as tattoos or scars, he said.
Appealing to the Vietnamese community, Det Ch Insp Pasmore said people in the UK illegally may be concerned for a relative but fearful of approaching the police.
He said Essex Police would “take no action whatsoever” against those who come forward.
Det Ch Insp Pasmore said he had also met the Vietnamese Ambassador to the UK, who had vowed to help with the identification process.
Addressing a press conference, he said he was unable to comment on “investigative elements” of the case.
However, he said there were “lines of inquiry that are set of course to establish whether or not there are wider conspiracies involved in this”.
“It must be clear that criminals, murderers are taking more and more chances with these vulnerable people and the risk is massive,” he said.