A Vietnamese man who ran multiple cannabis farms in Newcastle, England, was jailed on Monday. A year-long operation – dubbed Operation Banjo – brought Khanh Duy Pham, a 26-year-old drug lord, down.

He reportedly controlled five large cannabis farms in Newcastle, the BBC reported. According to Northumbria Police, Pham utilized illegal Vietnamese migrants as his primary source of labor.

The “linchpin” – as he was described by police – used fake documents and bank statements to rent properties which he converted into drug farms.

Detective Sergeant David Kay of the North East Regional Special Operations Unit said Operation Banjo started in 2016 to combat Vietnamese community-based organized crime in the local area. Pham was established as a person of interest during the investigations, Chronicle Live reported.

Pham ran his empire for years until Northumbria Police arrested him at his residence on Baxter Avenue in Fenham in July 2017.

He was charged with cannabis production. On Monday he pleaded guilty at Teeside Crown Court and was sentenced to four years in prison.

Sergeant Kay said his imprisonment makes the city a better place and said he hoped the sentencing will serve as a warning to others linked to similar crimes.