A ROYAL Marine jailed for the murder of a captured Taliban fighter in Afghanistan let professional standards “slip to an unacceptable low level,” a review found yesterday.

The Royal Navy internal review looked at events surrounding the shooting of the wounded man by Sergeant Alexander Blackman in Helmand province in September 2011.

Sgt Blackman quoted Shakespeare as he shot his victim in the chest at close range with a pistol after the Afghan had been seriously injured in an attack by an Apache helicopter.

He is serving an eight-year jail sentence for the war crime after a court martial convicted him of murder.

The navy released a redacted 12-page executive summary of its review into the incident.

It found that a combination of Sgt Blackman’s poor leadership, his rank, group conformity, moral disengagement and the mindset of the battlefield contributed to the incident.