John Young, 45, who was shot twice and awarded the Queen's Gallantry Medal while a serving officer, demanded pounds 30,000 to help influence the outcome of an Old Bailey trial last year.
Southwark Crown Court heard that, helped by an as-yet-unidentified serving officer, who was supposed to be part of a team providing 24-hour protection for the jurors, he obtained highly-confidential addresses of some of those trying the armed robbery case.
Passing sentence, Judge Gerald Butler QC told Young, who turned private detective after leaving the police force two years ago, that what he had done "strikes at the very roots of our system of criminal justice". He went on: "For that reason a deterrent sentence is inevitable.
Young, who was convicted earlier of "doing acts intending and intended to pervert the course of justice" between 13 March and 15 April, showed no reaction apart from turning to relatives in the public gallery and saying "All right".
Opening the week-long trial, Joanna Korner QC, for the prosecution, said Young had "spotted a potential to make a great deal of money". She explained that the Old Bailey case involved kidnapping, robbery and firearms. Each juror was being protected round the clock by two policemen.
"Regrettably the arrangements had the very opposite effect, because it enabled a corrupt police officer to obtain names and addresses of jurors and pass them onto someone who might have an interest in influencing the jury," she said.
The jury heard that Young, of Poplar Close, New Barn, Kent, approached the sister of one of those on trial as she left the Old Bailey public gallery and offered to supply her valuable information which would help her brother, in return for cash.
An undercover police surveillance operation resulted in Young's arrest.Reuse content