A leading modern slavery expert who pursues employers on behalf of exploited overseas workers, recovering thousands of pounds for them in the process, has received a threat on his life. Aké Achi, founder and chief executive of Migrants at Work, an organisation which protects workers’ rights, says the letter was posted to his home. It claimed to be from people employed to “maintain order”, and said Achi had been “busy causing lots of trouble and severe losses to our client” before warning him that his “time is up’’. The letter also threatened to harm his “partner and little ones” and made it clear that his family home was being watched. Achi challenges dozens of licensed sponsors each year that employ migrant workers. He has no idea which company is behind the threats or how they found his home address. “I never thought [my work] would bring so much trouble – to the extent that somebody would threaten me and my family. I would have expected to receive this letter if I was in Africa, back in my home country [Ivory Coast], but not in the UK.” Achi has expressed frustration at West Midlands police’s handling of the threat. The case was closed within 20 minutes of his sharing a photograph of the letter because it “did not fall into any crime category”, so the officer was unable to record a criminal offence. However, when police informed him that the incident was being recorded as stalking, Achi was optimistic. But within minutes of receiving that text message, he got another one saying there was “insufficient evidence”. A spokesperson for West Midlands police said the letter was “subject to a number of reviews” and the “investigation has been closed pending any further information coming to light”. Growing evidence of abuse towards people on work visas makes services provided by Migrants at Work increasingly important. Some migrants have paid thousands of pounds in illegal recruitment fees only to discover there was no job for them. Others have had wages stolen. In the run-up to the general election, Yvette Cooper, now the home secretary, promised an investigation into the treatment of migrant care workers – the group that makes up the majority of Achi’s clients. The deputy prime minister, Angela Rayner, also told the Observer of the party’s commitment to establish a new single enforcement body, the Fair Work Agency (FWA), to strengthen workers’ rights. Citizens Advice, one of several national organisations to refer clients to Achi, recently said the design of the FWA must ensure workers who are vulnerable because of their immigration status are able to access help safely. Achi, who describes his organisation as “the last line of defence” for migrant workers, said the threat would not stop his work.