THE investigation into the murder of Cai Guan Chen, codenamed Operation Caddy, was long and complex and was made harder by the fact that police were dealing with Chinese nationals.

The body of Mr Chen was found in a canal at Burn, near Selby, on March 20, 2009, but it took weeks for the police just to identify him.

The task was made harder because the pathologist initially believed the victim was between 15 and 25 years old. In reality Mr Chen was 38.

Detective Superintendent Karnail Dulku, who led the investigation, said that following a media appeal for the victim’s identity, a Chinese national in the UK came forward to say that a woman had been in touch as she had lost contact with her husband.

But because the missing husband was 38, the report was not initially treated as a priority.

But when other avenues of investigation were closed, which included sending artist’s impressions of the victim to Chinese communities across the UK, the police looked again at the missing husband.

An initial electronic fingerprint comparison with those prints held by the UK Borders Agency proved negative, but when officers persisted and compared the actual paper records they found a match.

This identified him as Cai Guan Chen, a former fish farmer and father of three.

Police had already found traces of blood at an illegal cannabis factory at Elvington, and a DNA match revealed it was the scene of Mr Chen’s murder.

But there were still huge difficulties because North Yorkshire officers were having to deal with Chinese nationals, some of whom were illegal immigrants, who already distrusted the police because of experiences in their own country. In some cases investigating officers had to organise covert surveillance operations just to find witnesses.

To add to the difficulty, Mr Chen came from Fujian province, an area with a population of 80 million people and its own dialect, different from Mandarin or Cantonese.

Marijuana cultivation is a capital offence in China and even Mr Chen’s own family, who knew about their relative’s murder and involvement with cannabis, were reticent about speaking to the police. Officers also found that their Chinese counterparts, although helpful, did not give them the freedom of movement they would normally have had.

The police travelled to China to talk not only to Mr Chen’s family but also a man known as The Apprentice.

He had been with Mr Chen when he travelled to York on January 2, but was arrested for not having a valid train ticket and deported. Police hoped he may have been able to help with their inquiries but were unable to trace him, later finding out he was somewhere in Inner Mongolia.

Chief Constable Grahame Maxwell said: “Considering the investigation began with an unidentified Oriental man, living illegally in the UK, in an underground community a long way from his family in China, the team has carried out a highly effective and dynamic investigation which underlines North Yorkshire Police’s effectiveness and capacity to investigate serious and organised crime and to bring those responsible to justice.”

He paid tribute to Detective Superintendent Karnail Dulku and his team of officers for their “painstaking, thorough and determined investigation in bringing this highly complex case to a successful conclusion”.

Mr Justice Butterfield also commended Det Supt Dulku, Det Insp Steve Taylor, Det Insp Nigel Farthing, Det Con Martin Hinchliffe, Det Con Ken Proctor, Det Con Karl Hardman, Det Con Alex Barber and Det Con Simon Dixon, saying: “This must have been a most difficult matter to investigate.”