No charges are to be brought against the Metropolitan Police officer who fatally shot Jermaine Baker, prosecutors have said.
The 28-year-old, from Tottenham, north London, died in 2015 as the result of a single gunshot wound during a Met Police operation in Bracknell Close, Wood Green.
He was killed as armed police swooped and foiled an attempt to free Izzet Eren as he was being transported from Wormwood Scrubs prison to Wood Green Crown Court on December 11.
The Crown Prosecution Service (CPS) had been investigating whether a criminal offence was committed by the officer, known as W80, who claimed to have acted in self-defence, believing that Mr Baker was himself reaching for a firearm.
"The CPS has concluded that there is not a realistic prospect of conviction," it said in a statement.
"The prosecution could not prove to the required standard that W80 was being untruthful about his belief that Mr Baker was armed and reaching for a weapon to fire on the officers.
"As the case does not meet the evidential threshold set out in the Code for Crown Prosecutors, no charges can be brought against W80."
The CPS investigated the shooting following a referral by the Independent Police Complaints Commission (IPCC) after uncovering evidence that could have pointed toward a criminal offence being committed by the officer.
Mr Baker was not found to be armed, although an imitation Uzi machine gun was recovered from a holdall in the rear foot well behind the driver's seat of the car.
"The officer claimed to have acted in self-defence, believing that Mr Baker was reaching for a firearm in a bag he was wearing and that he and his colleagues were in imminent danger of being shot," the CPS statement said.
"As a result of operational briefings the officers reasonably believed that the men in the car were dangerous individuals who were armed and prepared to use their weapons to achieve their criminal purpose.
"Although armed police may use lethal force where necessary in the line of duty, they are subject to the same laws of self-defence and the use of reasonable force as any member of the public.
"This means that the actions of an officer, including the use of pre-emptive shots with intent to kill, will be judged on whether they were reasonably necessary in the circumstances as he honestly believed them to be, even if that belief is mistaken."
Mr Baker was part of a group of men who were trying to help Mr Eren escape from a prison van as he travelled to the court to be sentenced.
The car Mr Baker was in had been bugged by police, and shortly before 9am armed officers surrounded the vehicle and he was shot.
Mr Baker was pronounced dead at the scene.
The IPCC said: "We are aware of the CPS decision today to take no further action in this case.
"Our report, including the investigator's opinion as to whether or not any officers have a case to answer for misconduct, has been provided to the Metropolitan Police Service and we await its response."
Mr Baker's family have have voiced "very serious concerns" about his death.
In a statement previously issued by their solicitor, they said: "We have very serious concerns about the circumstances in which Jermaine was shot.
"Our priority is to find out the truth and have anyone responsible for his death held to account. We look to the CPS to ensure that justice is done."
Last year they sought a court order to stop the officer who managed the operation from resigning from the force.
But the High Court bid failed, meaning that the tactical commander, known as Officer FE16, will not have to face possible disciplinary proceedings.
There was no suggestion that FE16 was resigning to avoid disciplinary action.
The Metropolitan Police said its Directorate of Professional Standards is considering whether any misconduct proceedings should be taken against officers.
Deputy Assistant Commissioner Peter Terry said: "Our thoughts continue to be with Mr Baker's family at this difficult time. It is completely natural that they want answers as to how he lost his life.
"We continue to provide the firearms officer, his family and all his colleagues who were deployed on the operation that day with every possible support.
"As police officers, we are all fully aware that we will be asked to account for our actions. We are not exempt from the law and would not wish to be.
"Firearms officers are highly trained, highly skilled and very experienced. On that day they were doing exactly what we, the MPS, ask of them, which was to protect the public of London from armed and dangerous criminals."
He added that following the recent London terror attacks "so fresh in the public's mind, it is clear why now, more than ever before, our armed officers provide an invaluable service in keeping Londoners and their own unarmed colleagues safe.
"We all rely on them to take decisive action, without hesitation, in the face of the enduring threat from terrorism. This role requires them to face and quickly assess threats beyond the obvious such as the overt possession of a gun or knife, but those threats that could result in an immediate significant loss of life."