A major human trafficking trial has ended after nine people admitted bringing Latvian workers to the UK and housing them in appalling conditions.
The gang was arrested after police raided homes in Derby and Latvia in September 2017 and February 2018.
Nottingham Crown Court heard at least 30 people were trafficked over five years, but the figure could be higher.
Derbyshire Police said it was the biggest modern slavery case it had ever investigated.
The court heard vulnerable men were recruited on the promise of work in the UK.
They got jobs in food factories around Derby and were housed in sub-standard accommodation.
The Derbyshire force said officers worked with Latvian police to find the people responsible for recruiting the victims.
The gang - comprising five men and four women - originally denied offences linked to human trafficking with a view to exploitation, but changed pleas seven weeks into a three-month trial.
The trial heard the enterprise was headed by 54-year-old Ainars Pelcis, described as the "gypsy baron" because of his power and wealth.
On Wednesday, Pelcis, of Rutland Street, Derby, admitted a charge of conspiracy to arrange/facilitate entry into the UK for exploitation, along with eight others. They are:
- Ilgvars Pelcis, 33, of St James Road, Derby
- Karlis Aleksandrovs, 42, of Patmore Square, Derby
- Magdalena Kleina, 55, of St James Road, Derby
- Jolanta Pelce, 37, of Patmore Square, Derby
- Karens Pelcis, 25, Vincent Street, Derby
- Madara Stromane, 24, Rutland Street, Derby
- Andris Krauklis, 39, Vincent Street, Derby
- Imitra Didzis, 33, Talsul Tukums Latvia
Forced labour charges against all the gang members were dropped, but Judge James Sampson said his sentencing would make a "finding of fact" that it happened.
Other charges against two remaining defendants, Jana Pelce and Mareks Kaira, have been dropped.
Sentencing is due to take place on 7 November.