Video: David Cameron: Andrew Mitchell police allegation 'very serious issue' The Prime Minister promised police will get to "the truth of the matter," after fresh evidence suggesting an officer may have pretended to be a member of the public and fabricated an account of the incident. In his weekly questions in the Commons, he said: "A police officer posing as a member of the public and sending an email potentially to blacken the name of a Cabinet minister is a very serious issue and does need to be seriously investigated. The Metropolitan Police Service is conducting a thorough and well-resourced investigation to get to the truth of the matter as quickly as possible. The Independent Police Complaints Commission will be supervising the investigation and I think we should allow them to get to the truth. Mr Mitchell stepped down earlier this year, after two police officers accused him of calling them "f - ing plebs" in a row over a bicycle. It has now emerged that a third officer wrote an email to John Randall, the deputy Chief Whip, claiming to be a member of the public who witnessed the row.