What we also now know, is that once the pathologist, Peter Venezis, removed the badly fragmented bullet from Sheila's neck, he handed it (PV/20) to police - in particular, SOC took control and possession of it, together with all the other crime scene ammunition. Establishing at what stage the badly fragmented bullet was swapped over, must have involved co-operation of SOC, and the dodgy ballistic expert, Fletcher, with or without the knowledge of the pathologist (Venezis)...
If there was a conspiracy to tamper with the crime scene ammunition, it must have involved DI 'Ron' Cook (SOC), Malcolm Fletcher (ballistic expert), and Peter Venezis (pathologist)...