Two former police chiefs have questioned why the officer who shot dead unarmed teenager Michael Brown in Ferguson, Missouri, didn’t retreat after his initial encounter with him and wait for back-up.

Officer Darren Wilson, in a recent TV interview about the tragedy, said ‘I did my job right’. However, former officers with decades of experience have cast doubt on that statement.

Wilson, in his testimony to a grand jury, said that after asking Brown to move onto the sidewalk from his car, he punched him in the face and tried to grab his gun ‘with the most intense aggressive face’.

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Officer Darren Wilson, in a recent TV interview about the Michael Brown tragedy, said ‘I did my job right’

Former police chiefs believe Wilson could have made a tactical retreat after the struggle with the gun with Michael Brown (pictured)

He explained that he fired the fatal shots after Brown charged at him, having ignored his orders to get on the ground several times.

When ABC’s George Stephanopoulos asked Wilson if he could have prevented the death, Wilson replied ‘no’.

But Eugene O’Donnell, a professor at John Jay College of Criminal Justice and a former New York City police officer, disagrees.

He believes Wilson could have made a tactical retreat after the struggle with the gun.

He told the New York Times: ‘There certainly wouldn’t be a prohibition of him driving a little further along and regrouping, calling for help and thinking about nonlethal weaponry. Just because you’re a police officer doesn’t mean you have to go into a situation headfirst.’

Vincent E. Henry, whose career with the New York Police Department spanned 21 years, including undercover work, agrees.

Former Boston police commissioner Edward Davis (right) said it was disappointing that Wilson didn’t use a Taser or pepper spray to defend himself

He told the paper: ‘To back up and maybe follow him until backup arrived, in retrospect it might have been a better choice.’

Another former officer questioned the use of a lethal firearm to deter Brown’s aggression.

Edward Davis, who retired as Boston police commissioner last year, said it was disappointing that Wilson didn’t use a Taser or pepper spray.

However, there was also some sympathy from experts over Wilson’s handling of the situation.

Henry said ‘Who would want to get punched in the face and then kind of say, “Let me just back up and follow this individual”?’

While Fred Bealefeld, a Baltimore police officer for 31 years, told the New York Times: ‘If someone grabs your weapon, as a cop you’re not thinking they are going to scare you with it. In my mind…they were going to try to kill me.’