Reminder to police: it is not good practice to doctor evidence

That the police shot dead the wrong man was a mistake. That one officer has been force to admitt doctoring the records of exactly how and why they came to shoot him threatens to turn the mistake into something more enduring.

The notes of the officer – identified only as "Owen" at the inquest of Jean Charles de Menezes – were altered the day before being submitted as evidence to a Metropolitan Police solicitor earlier this month. The officer told the court he did not see the deleted evidence as relevant, even though it appeared to contradict the testimony of Deputy Assistant Commissioner Cressida Dick, who led the ill-fated operation resulting in Mr de Menezes's death.

The former Metropolitan Police Commissioner Lord Imbert said last night that the doctoring row is a "wake-up call" for officers.

The Met faces intense scrutiny over the shooting of the Brazilian electrician in Stockwell in 2005 after he was mistaken for a failed suicide bomber. Public confidence has been sapped by the recent resignation of Sir Ian Blair and a spate of race rows involving senior officers.

Lord Imbert, who led the force between 1987 and 1993, said last week's revelation, that a Special Branch officer had altered notes submitted to the inquest as evidence, presented an opportunity to remind officers of correct procedure. "It is certainly not acceptable to alter your notes," he said, and condemned the doctoring of evidence as "not good practice".

"This is a wake-up call, and officers must be reminded of the correct way of doing things." He added that the practice of officers collaborating to produce a single written statement, while not wrong, should also be kept within "proper limits".

Anthony Scrivener QC, former chairman of the Bar Council, went further and said "What is needed is a reminder of the rules regarding taking statements," he said. "You can alter it, but it has to be by way of an official statement. A police officer should not decide what is relevant or not. That's for the court to decide."

The Independent Police Complaints Commission (IPCC) and the Metropolitan Police Authority will now investigate the officer's actions.

The controversy is likely to swell the growing numbers making formal complaints to the IPCC. The IPCC's latest figures reveal public complaints over "irregularity in relation to evidence/perjury" have almost doubled in the past four years – rising from 493 in 2004 to 931 in 2008. And the number of complaints made each year accusing police of "corrupt practice" has almost tripled over the same period – up from 91 to 251.

A Metropolitan Police spokeswoman said: "The Met continuously reviews policies and procedures to ensure we can deliver greater policing and operational effectiveness. We will of course consider any options for learning and best practice that may arise from the inquest."