Police marksman: 'I will have to live with this for the rest of my life. I am sorry'

A police marksman choked back tears yesterday as he recalled the moment he became convinced that Jean Charles de Menezes was a suicide bomber about to detonate a device.

The officer from Scotland Yard's CO19 firearms unit, identified as C12, described how he shot Mr de Menezes at point-blank range when the innocent Brazilian got up and walked towards him even after he shouted "armed police" and pointed his gun at him.

He said at that stage he believed he was "going to detonate" and he had to act to prevent the bomb going off. Mr de Menezes was shot seven times in the head after being mistaken for failed suicide bomber Hussain Osman.

Giving evidence in public for the first time at the inquest into the death of Mr de Menezes, C12 said he came face to face with him inside a cramped Tube train at Stockwell Underground station in south London on July 22 2005.

He said he recalled a scrum-like "ruck" as he pointed a gun towards Mr de Menezes's head, while a surveillance officer, identified as Ivor, pinned down the Brazilian .

"I brought the handgun up from my leg and pointed it up to shoulder level," he said. "He [Ivor] immediately grappled him into his seat. It just reconfirmed to me that I had to use force as soon as possible. If there was any alternative, you must believe me, I would have taken it but I did not have any alternative.

"I did not believe I had an alternative and if I did not act, members of the public would be killed. My colleagues would be killed and I would be killed. I had a duty to protect the public."

He said his Glock pistol was next to Ivor's head as he opened fire. "We were all together and it was a bit of ruck... I remember the gun coming into contact with Ivor's head in order to get to Mr de Menezes. I do not know how close it was. I honestly believed this man to be a suicide bomber."

C12 described his feelings when he learnt the next day that the man he shot was not Osman. He said he felt "a sense of disbelief and of shock, sadness, confusion". "Everything I have ever trained for – for threat assessment, seeing threats, perceiving threats and acting on threats – proved wrong.

"And I am responsible for the death of an innocent man. That is something I have to live with for the rest of my life."

Addressing Mr de Menezes's mother and family who were in court he said: "I can't begin to put myself in the position that they are faced with. I am a family man myself and to lose a son or any member of your family in this situation – I just couldn't believe it. And I offer my sincere condolences, I really, really respectfully do that."

But C12, who told the inquest he had never shot at a suspect before, earlier spoke of his fears that he might not return from the operation alive. He said: "The whole journey, if I can call it that, was an extremely emotional one for me. Both at the time of the briefing, listening to the briefing and listening to the nature of the threat and the danger these people posed, and possibly not going home again at the end of the day."

The firearms officer also told the inquest that the quality of radio communication was "awful" in the minutes before Mr de Menezes's was shot. He said: "They were so bad that I distinctly remember hearing thinking that another channel is coming over into our channel.

The coroner asked him whether he meant that the radio signal was "weak, faint or fuzzy, so that you couldn't understand what was being said, or what?" C12 replied: "All of those – it was awful."

C12 was asked why he shot Mr de Menezes three times. He replied: "I had to be certain that life was extinct, that there wasn't any more threat, that this person couldn't detonate a bomb.

"Our training is, or has been, that a critical shot is a single shot, probably to the base of the skull, which will cause instant paralysis. I was not in a position to get there to do that. I fired the number of shots because I detected moments, albeit it might have been movement caused by the bullets." C12 also said he would not have fired at Mr de Menezes if he had remained seated or if he had stopped approaching him when he shouted "armed police".

The inquest was halted briefly after C12 became distressed by his recollections and could not continue. When it resumed, he recalled being "covered in blood" after the shooting. He and C2, the other firearms officer who shot Mr de Menezes, checked each other to ensure they had not been wounded in the incident.

The victim's mother, Maria Otone, held back tears as she emerged from the hearing. Through her translator, Mrs de Menezes, who lives in Brazil, said that hearing the evidence had been "very difficult". She added: "It's been very difficult for us to listen to everything that's been said, but we want to be here every day because we want to hear the truth."

The inquest was adjourned until Monday, when C12 will be cross-examined by the De Menezes family's barrister, Michael Mansfield QC.