Police busted a cannabis farm containing 196 plants before raiding the house next door.
Officers arrested two men and now they are investigating if there are more drug farms in the chain.
One of the houses in Tankerville Street, Hartlepool, had 196 cannabis plants under cultivation.
A Vietnamese man, who claims he was trafficked into the UK, was caught with suspicious photos on his mobile phone.
The gardener Minh Van Nguyen, 26, said he entered the UK illegally in 2009 and he was driven up to the address four months ago from London.
Prosecutor Emma Atkinson told Teesside Crown Court he had said he had been offered money to look after the plants.
He said that he had accepted it because he needed money for his heart problem and he could not register with a doctor because he was in the country illegally.
Miss Atkinson added: “He said that he did not know the people who owned the house.
“He said that he did not engage with anyone other than a Vietnamese male who would turn up to tell him what to do, normally to water the plants.”
Ms Atkinson said the house next door was also raided on the same day, May 3, and another cannabis farm was discovered and a second man Au Nguyen, 24, was arrested on suspicion of cannabis production.
Mobile phones were seized from both houses, and the phone seized from Minh Van Nguyen had photographs of a man in different locations in other parts of the country.
She told the court she was waiting to ask the officer in charge of the case if the photographs were linked to Minh Van Nguyen.
Miss Atkinson added: “That would be a different slant on where the Crown would place it for sentencing guide lines in relation to the role that the defendant played, significant or a lesser role.”
She said the Crown was in touch with the Home Office about Au Nguyen, who claimed that he was trafficked into the UK.
Photographs found on a phone at his house were also being examined.
The men appeared separately over videolinks from Holme House Prison in Stockton.
Minh Van Nguyen, was further remanded in custody until June 15 after he pleaded guilty to producing cannabis.
Au Nguyen faces a similar charge, but he was not asked to plead. He was remanded in custody until July 20.