Jean Charles de Menezes was the victim of "terrible and extraordinary circumstances", the senior policewoman in charge of the operation that led to his death told an inquest today.
But Deputy Assistant Commissioner Cressida Dick insisted that none of the officers involved did anything wrong.
Ms Dick listed a series of "unfortunate" coincidences as she gave evidence to the inquest into the shooting of the innocent Brazilian electrician.
* the fact that he lived in the same block of flats as failed 21 July suicide bomber Hussain Osman;
* the fact that he looked "very like" Osman;
* the fact that the first surveillance officer was "indisposed" and only got a short glance at him;
* Mr de Menezes's innocent behaviour in getting off and then back on a bus;
* and the fact that he entered the Tube station used by three of the 21 July bombers the previous day.
Mr de Menezes, 27, was shot seven times in the head at Stockwell Tube station in south London on 22 July 2005 by police marksmen after being mistaken for an on-the-run terrorist.
Ms Dick led the Scotland Yard control room overseeing the pursuit of the Brazilian by surveillance and firearms officers who feared he was Osman.
Asked what went wrong, she told the inquest: "One thing that clearly went wrong was that we as a nation did not manage to prevent those attacks on July 7 or indeed Hussain Osman and others' attacks on the 21st.
"Mr de Menezes was the victim of some terrible and extraordinary circumstances the day afterwards.
"He was extraordinarily unfortunate to live in the same block as Hussain Osman had been, he was desperately unfortunate to look very like Hussain Osman.
"There are some things that happened - for example the fact that the first surveillance officer was indisposed and only able to get a relatively short glance.
"Mr de Menezes waited only a very short time at the bus stop so - as I understand it today, I didn't know that at the time - therefore a surveillance officer again would not have a great ability to look at him properly.
"Some of the things that Mr de Menezes did in all innocence - the way he behaved, the way he came off the bus and on the bus - contributed to my assessment of him as a bomber from the day before, and someone who might be intent on causing an explosion today.
"And finally the thing I would say last is he had the great misfortune of entering the same Tube station that three of the bombers had entered the day before.
"So lots of things happened, any one of those you might describe as going wrong."
But the senior officer added: "If you ask me whether I think anybody did anything wrong or unreasonable in the operation, I don't think they did."
Ms Dick was watched in the courtroom at the Oval cricket ground by the shot Brazilian's mother, Maria Otone de Menezes, who attended the hearing for the first time today.