Scotland Yard is bracing itself for a “cutthroat” public showdown in which officers blame one another for the shooting of Jean Charles de Menezes, the Brazilian electrician, on a Tube train three years ago.

The Metropolitan police’s rival firearms and surveillance teams have hired separate lawyers to attack each other at the inquest into the shooting at Stockwell station in south London in July 2005.

Sir Ian Blair, the Metropolitan police commissioner, fears that the hearing in September could turn into a month-long show of public infighting as his officers try to defend themselves under questioning by Michael Mansfield QC, the barrister for the de Menezes family.

The officers are said to be preparing what is known in legal circles as a “cutthroat” defence – two witnesses seeking to destroy each other’s credibility as each claims that the other was implicated in a crime.

One senior official said last week: “It’s going to be a right mess. You’ve got the surveillance teams and the firearms teams utterly opposed to each other. It’s going to be an unedifying spectacle.”

For almost two years, resentment has been simmering between the rival Met units involved in the disastrous surveillance operation that led to de Menezes, 27, being shot dead by two firearms officers.

Police had mistaken him for one of the four fugitive terrorists involved in the failed suicide bombings of July 21.

After reviewing the case papers, Richard Horwell QC, the force’s senior counsel, has advised Blair that there is a fundamental conflict in the police evidence. The contradictory accounts mean that as many as six separate groups of officers will have their own lawyers at the inquest – all at public expense.

The two firearms officers who killed de Menezes – so far referred to only as Charlie 2 and Charlie 12 – will testify in court for the first time. They are among at least 42 Met officers being called. Many have not previously given public evidence and have applied for their identities to be kept secret.

Officials say the two marksmen are privately furious about the way their colleagues on the surveillance teams handled the shooting and its aftermath.

Two bones of contention will be the decision to alter an observation log after the shooting and why the firearms unit took 4½ hours, rather than one hour, to arrive.

The delay meant the Brazilian was not intercepted until he was already on the Tube. Officers say they believed he was about to detonate a suicide bomb and had little choice but to kill him.

Last year the Met as a corporate body was found guilty at the Old Bailey of endangering the health and safety of the Brazilian.

Senior officers said that if the inquest jury returns a verdict of unlawful killing, it could end Blair’s career as commissioner of the Met.

One said: “The Stockwell thing is going to be high drama. It might be bad news for Sir Ian. If the Met is found guilty of unlawful killing, I can’t see how anyone could survive that.”

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