A former Scotland Yard officer arrested over allegations of unauthorised leaks to a journalist has asked to play a key role in the judicial inquiry into press standards.
Ex-detective chief superintendent Dave Cook yesterday requested core participant status, which means he is able to cross-examine witnesses who appear before Lord Justice Leveson.
Mr Cook, 52, who returned to work as an investigator for the Serious Organised Crime Agency this week after six months off sick, is understood to have encountered "obscene corruption" while at the Met. A source close to the inquiry claimed he is due to give evidence to Leveson and could reveal the full scale of alleged wrongdoing he encountered at the force.
Mr Cook was questioned yesterday on suspicion of misconduct in a public office and bailed. The Independent Police Complaints Commission had been passed information by Met detectives from Operation Elveden, investigating alleged payments to police officers by newspapers.
In 2002, Mr Cook led a Met investigation into the axe murder of private eye Daniel Morgan in Sydenham 25 years ago. Main suspects included Met officers and private investigators who also worked for the News of the World. The investigation collapsed last year amid criticism of police evidence.
Soon after Mr Cook made a fresh appeal about the case on Crimewatch in June 2002, he discovered he was under surveillance by men working for the defunct Sunday tabloid.
Mr Cook, whose phone was hacked by the NoW, challenged then editor Rebekah Brooks in December 2002. She admitted the paper had been following him but claimed it was investigating whether he was having an affair with Crimewatch presenter Jacqui Hames. However, it was well-known the pair were married.
Today, a friend said of the leak allegations: "I believe this arrest is a measure to quieten him down ahead of his involvement in the Leveson inquiry. He knows where all the bodies are buried. This is an attempt to blacken his name."