Early on in her investigation into the shooting of David 'Noddy' Rice at Marsden Lea car park, South Shields, in May 2006, Detective Superintendent Barbara Franklin, learned that prime suspect Allan Foster claimed to have an officer he called "copper John" on his payroll.

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It was a relationship which hampered the investigation into the murder, for which police later said Foster was responsible.

Dept Supt Franklin tipped off Detective Superintendent Ian Dawes, head of Northumbria Police's integrity unit.

Det Supt Dawes said: "John Jones's name came into the frame within the first few days of our investigation.

"We had his name, but we had to confirm we were 100 per cent dealing with the right individual.

"The investigation team did a fantastic job. This was a very complicated and protracted inquiry.

"A lot of the investigations were based around telephone evidence, and officers travelled to London to track witnesses down.

"Three such witnesses were the call girls who, by virtue of their profession, were reluctant to get involved in police investigations.

"The investigation in London was very time-consuming."

Det Supt Dawes said his team had authority to have Jones under surveillance for the year leading up to his arrest, but he was not under observation constantly.

The officer said Jones's failure to provide his colleagues with information about Foster had hampered the investigation into Mr Rice's murder.

Det Supt Dawes said: "The failure of a serving police officer to provide information of this nature in such a high-profile investigation underlines how corrupt he became."