Question: Scenario brief: Someone is murdered, possibly arranged collisions involved, how would your job support in solving this murder? Note: We know they've been murdered, unsure about burial or time of death or how. (By the way, I'm setting more of these scenario questions with more details in every brief question!)

Mark Hill answered on 22 Mar 2011:

Hello Bones,

I am currently writing up a report into a murder, with a couple of vehicles involved, which were then ‘torched’. That has incorporated a lot of my skills in forensic analysis of vehicle parts, identifying vehicle types, linking vehicles to the scene, with refractive index analysis of glass, and mechanical fit of a vehicle onto street furniture.

When called to a scene, in which crime is involved, as opposed to a more straightforward road crash, I will consider calling Scenes of Crime Officers (SOCO) to the scene. Before a full examination takes place, the collision investigator (CI) and the SOCO will identify the scenes, by number. For example the locus will be one scene, a body at a hospital would be another scene, vehicles no longer at the crash, which have failed to stop, become scenes, as does anyone arrested from the scene. The SOCO and CI then ensure that separate SOCOs and CIs, not having attended the locus, deal with the other scenes, to prevent cross-contamination of evidence.

A strategy is then set out between the CI and the SOCO, listing who will deal with which aspects of the investigation. Having dealt with examination, including tapings, swabs, blood pattern analysis, body kinematic measurements (seat positions, angles, angles of mirrors, steering column)evidence gathering (removal of air-bags, seat belts, bulbs etc), photography, electronic survey and supervised careful recovery of the vehicles for later mech examination, I will usually do a couple of skid tests, to give frictional values for calculations. At the mechanical exams I will conduct pretty much an MOT test on the vehicle. Where wheels have been torn off I may seal brake ines and charge the systems, to determine brake efficiencies. Tyre pressures, checked at the scene, are checked again. Pressure tests are sometimes conducted.

Both SOCO and CI will go to the post mortems, which would be done by an H O Pathologist. These are a lot more detailed and I will usually discuss in depth how injuries may have been caused, by explaining the collision dynamic.

I produce a scale plan and composite plans to assist with understanding the location.

Neither CIs or SOCOs will take witness statements, but I will see all statements, copies of interviews, copies of any CCTV evidence – buses have a minimum of four cameras now, sometimes eight.

SOCOs, CIs and Detectives will discuss forensic submissions that may be made to labs out of the force area. I will advise on the potential strengths of the forensic evidence, with the SOCOs.

I may conduct tests and reconstructions, with similar vehicles and in similar settings, to replicate the pre-impact movements of vehicles and people.

Then the writing and maths start, in order to formulate a detailed report. My report typically is in excess of 12 000 to 15 000 words, or 40 to 50 pages, with reference papers and calculation sheets appended to the report. I will comment on the evidence available and how witness evidence is either ‘consistent with’ or ‘at variance to’ that evidence. The physical evidence takes precedence in my investigations, which is where the scientific mind comes in.

I hope that I have answered your question. It is not an easy question to answer in a short manner, in a forum such as this.

Thank you.

Mark.