A former police firearms officer, identified only as E7, is to be charged with the murder of Azelle Rodney, who was shot dead in north-west London during a police operation in 2005.

The decision to charge E7, who has been granted anonymity, follows two inquiries by the Independent Police Complaints Commission into the killing.

Rodney, aged 24, died in Edgware after officers stopped the car he and two other men were travelling in. The police feared that they were armed and on their way to rob Colombian drug dealers. Rodney was hit six times, in the arm, back and head. The public inquiry into his death, chaired by Sir Christopher Holland, ruled in July 2013 that there was no lawful justification for the shooting.

However, it was suggested on Wednesday that the decision to proceed with the charge could result in armed police officers rethinking whether they could continue.

The national police lead for armed policing, Simon Chesterman, said on Twitter: "Carrying a gun on behalf of the state is a big ask that just got bigger. Justice will prevail." He was later quoted by the Times as saying: "Firearms officers volunteer for the role and many are now considering their future career choices."

Announcing the decision to proceed with the charge, Alison Saunders, the director of public prosecutions, said: "Azelle Rodney died after the discharge of a police firearm on 30 April 2005.

"Following the outcome of the public inquiry, the Independent Police Complaints Commission re-referred the matter to the Crown Prosecution Service, providing us with the evidence previously gathered and the further evidence and material which has emerged since the initial referral.

"We have carefully considered the new file of evidence submitted to us and have decided that a former Metropolitan police officer, currently identified only as E7, will be prosecuted for murder.

"We have determined that there is a realistic prospect of conviction and that a prosecution is in the public interest."

The officer will appear at Westminster magistrates court for a preliminary hearing on 10 September.

In a statement, the Metropolitan police said: "The former officer was granted anonymity at the public inquiry into Mr Rodney's death and was referred to as E7. As criminal proceedings are now active, it would be inappropriate to comment further on this case at this time.

"The [Metropolitan police] runs firearms operations daily to take guns off the streets. Our officers are highly trained and professional and fire shots only once or twice a year. We accept that where this happens, our officers will be subject to detailed scrutiny.

"We keep our firearms tactics constantly under review and have accepted the recommendations made by the public inquiry into Azelle Rodney's death."

Rodney's mother, Susan Alexander, said: "I am very pleased at the CPS's decision to prosecute the officer who killed my son. I have waited a long time to see this day and hope this prosecution will lead to justice for Azelle."