Had accident and the other party moved their vehicle before the police was called

I was involved in an accident in 2009 and the other party moved their vehicle before the police were phoned, everyone is saying that it is my fault and I was speeding I was doing 25 in a 30 and they turned in to me as I was overtaking. As said previously they moved their vehicle I left mine where it stopped how can they have a case against me when the other party moved vehicle (evidence)? Please reply as I thought it was illegal to move and even if not the evidence was tampered with shouldn't this be perverting the course of justice?