Evaldas Medelis (left), 29 and Laminonas Navickas, 23, both of no fixed address, admitted production of cannabis.
However, Karolis Rusevicius, 27, of Mapperley Plains, Nottingham, was found guilty of production of cannabis, possession of cannabis with intent to supply, two counts of possession of criminal property and possession of a firearm and ammunition following a four-day trial.
The court heard the sophisticated and well-established operation had been uncovered after a member of the public reported seeing a suspicious vehicle at the empty Bethlehem Street property, and that there was a strong smell of cannabis.
Checks on the van revealed it had been reported stolen and it was stopped by our officers a short time later.
Medelis and Navickas were arrested after 80 cannabis plants (pictured) were found in the back.
A subsequent search of the building uncovered a number of growing areas had been constructed, with hundreds of plants up to 3ft high, along with a sophisticated lighting and watering system. The electricity supply had also been bypassed
Officers also discovered a disguised hatch leading into the kitchen of the neighbouring flat, where it was clear the growers had been living.
Forensic evidence found in the buildings led us to Rusevicius, who was living in a £600,000 property in Nottinghamshire.
Detective Constable Philip Jacobs, who led the investigation, linked in with our colleagues at Nottinghamshire Police and Rusevicius was arrested by their teams.
He was caught in the middle of counting out £20,000 in cash, while a further search of the property uncovered a handgun, live ammunition and two large vacuum bags of cannabis.
Welcoming today’s sentencing DC Jacobs said: “We come to work every day to keep people safe and targeting organised criminals like this gang is a big part of that.
“I hope this will serve as a warning to other organised crime groups that Humberside is not somewhere where their activities will be tolerated.
“This was a very sophisticated set up – one of the largest I have ever dealt with – and in uncovering it we have prevented them from pocketing more than half a million pounds. We have also taken a gun off the streets.
“This case also shows the importance of getting in touch with us if you have information about crime in your area – this investigation started with a call from the public to report a suspicious van.
“If you have concerns about anything please get in touch. We may not always be able to act straight away but we will always listen and every piece of information we receive contributes to our ongoing investigations and future operations.