Police say there will be no prosecutions after three people were arrested during a raid on a flower-picking farm earlier this year.
Devon and Cornwall Police executed a warrant at Bosahan Farm in February on suspicion that offences were taking place against migrant workers.
The operation was carried out under modern slavery legislation at daffodil fields near Helston in Cornwall.
Police said the case was investigated for five months.
But the force said that after discussions with the Crown Prosecution Service, there would be "no criminal matters pursued by police in relation to the investigation".
Devon and Cornwall Police said it "appreciated the disruption" the operation caused to the farming, agricultural and migrant worker community.
But it said it was important to recognise that officers had to "ensure the response to serious allegations of modern slavery were followed up and responded to with the gravity this under-reported crime deserved".
Two hundred people, mainly from Romania and Lithuania, lived and worked on the farm.
On the evening of the raid, many of them gathered at Camborne police station to protest against the arrests.
Justinus Stanislaus, a Lithuanian translator who was helping the group, said: "They want to prove to the world that they are not victims of modern slavery.
"It's a wonderful place to work and they are treated well. They refute everything that has been said in that respect."
Devon and Cornwall Police have refused to answer questions on whether they plan to respond to the workers' request for a public apology.
The force said said that following the raid, 14 people had chosen to leave the farm, which is in Manaccan.
It said 13 of them either found alternative employment or returned back to their home country.
Police also said that the farm involved had not been prevented from operating during the investigation.