A man who rented hundreds of properties to criminal gangs to be used as brothels and cannabis farms has been jailed for seven years and four months.
Chinese national Feng Xu used multiple false identities to get accommodation, the National Crime Agency (NCA) said.
His arrest in Birmingham in May was part of a major investigation into modern slavery and human trafficking.
He had previously admitted 22 fraud, false identity and money laundering offences at Birmingham Crown Court.
Investigators said the 43-year-old was a "prolific operator" and an "important enabler" for different criminal networks involved in prostitution, drug production and housing illegal immigrants.
Women were exploited at the properties that were used as brothels and there are criminal investigations under way in connection with Feng's case, the NCA said.
He ran his network for more than three years up until his arrest at his home address in Holliday Street, Birmingham, on 14 May. During that time, more than £4m was paid out in rent.
Among items seized by officers were 31 false or fraudulent Chinese and Portuguese passports, along with £94,000 in cash.
One computer database listed 446 different addresses which Feng - who had lived illegally in the UK since 2000 - had been involved in renting, investigators said.
Matt Rivers, branch commander at the NCA, said: "Using numerous false identities and false documentation he was able to supply hundreds of different properties across the UK.
"We believe that taking him out will have caused significant disruption to a number of different organised crime groups involved in sex trafficking and drug production."
Feng will face deportation after serving his sentence.
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