An investigation was launched by Independent Police Complaints Commission (IPPC) after the officer, who could have fired the shot which killed Saunders, was reportedly reprimanded by his superior shortly after his testimony on September 27.
A transcript of the officer's evidence allegedly contained song titles including 'Enough is Enough' by Donna Summer, 'Point of No Return' by Buzzcocks, 'Line of Fire' by Journey, 'Quiet Moments' by Chris de Burgh, 'Kicking Myself' by As Tall As Lions and 'F**k My Old Boots' by the Membranes, The Guardian reports.
A Metropolitan Police spokesman confirmed: "We have now been informed by the IPCC that they will manage an investigation by the Metropolitan police Directorate of Professional Standards."
"[The force] takes this matter extremely seriously as we expect the highest standards of all of our staff. The officer has been removed from operational firearms duty."
It was not confirmed which song titles were thought to have been inserted into the testimony of the unnamed officer, known as Alpha Zulu 8.
Saunders' mother Rosemary said: "If it's all such a game, was it a game on May 6? If this man can approach the inquest with such an attitude, then it makes you wonder about how he approaches shooting his gun to kill a man."