CSI: Crime Scene Idiots

What i’m reading now:

Gunshot Wounds: Practical Aspects of Firearms, Ballistics, and Forensic Techniques by Vincent J. M. Di Maio.

I’m doing a final year project which will involve using firearms to generate high velocity impact spatter. A bit of background reading around firearms will probably come in handy!

Review coming soon!

Anonymous asked: cast bloodstains

Anonymous asked: expirated blood

What about it?

Anonymous asked: impact splatter

Yes…?

(*spatter)

Book Review: Real Crime Scene Investigations by Connie Fletcher

Pros

• Provides lots of ‘mini stories’ for many untold cases.
• The stories are categorized by the content, rather than the author, if you are looking for cases of a particular content (e.g. decomposing bodies).
• Is very easy to read, as the book contains both very short, and much longer stories (some lasting several pages), so it can easily be picked up for a bus ride, or for a long read.

Cons

• There is no index, so if you wanted to read all of the memoirs of one contributor, you have to look at every page and find the name.
• It can be difficult to determine what is just the start of a new paragraph in the same story, or the start of a different story, as the layout is not very bold.

This isn’t really an educational book, although I suppose it could be considered as one? It is basically a collection of ‘memoirs’ of pathologists, crime scene lab managers, trace evidence analysts, scenes of crime officers etc. It is a really good read if you just want to find out what actually happens, and learn about a few interesting events that have happened in actual cases. But that is all you get, it assumes that you already know a decent amount about forensic science, so it doesn’t really explain much.

So, what exactly is DNA?

Its fairly safe to assume that most people know about DNA profiling, and about how a DNA profile can identify a person. But not a lot of people know what DNA is, or why it is unique to each individual… Here are a few basic points, expanding the knowledge of DNA profiling.

• DNA is made up of 4 nucleotide bases: Adenine, guanine, thymine and cytosine.
• DNA is a double stranded, anti-parallel, double helix structure.
• The nucleotide bases also consist of a deoxy-ribose sugar and a phosphate group.
• The order in which the nucleotide bases are placed along the double helix structure is what makes DNA unique to each individual.
• Every person in the world has their own DNA profile, with the exception of identical twins, who share a profile.
• The majority of a persons DNA is the same as everyone else’s, only a small portion is different.
• DNA sequencing techniques became widely used in 1977 when Frederick Sanger developed the dideoxy terminator sequencing technique [1].
• New technologies are being developed to sequence the whole human genome within 15 minutes [2].

[1] Sanger, F., Nicklen, S. & Coulson, A. R. (1977) DNA sequencing with chain-terminating inhibitors. Proc. Natl. Acad. Sci. U.S.A. December, 74 (12): 5463-5467.

[2] Broadwith, P. (2012) Viral genome sequenced. Chemistry world. 9(4), pp. 26.

Expirated blood spatter

Expirated blood spatter is a type of impact spatter. Expirated blood is blood that has passed through the trachea (windpipe) and is blown out of the mouth or nose, causing an array of small droplets.

Common markers of expirated blood include:

• the outline of air pockets in the blood pattern (where air has mixed with the blood as it is expirated)
• the presence of salivary amylase or other oral bacteria
• saliva trails (made in blood, rather than saliva)

The only confirmatory test for expirated blood, as of yet, involves testing the blood for the presence of salivary amylase or oral bacteria, commonly streptococcal bacterias. These tests involve the PCR method of increasing the quantity of substance present, then testing individual components [1][2].

An example of a case involving expirated blood is the murder of Billie-Jo Jenkins, whose foster father, Sion Jenkins, was acquitted of her murder after spending 6 years in jail. Part of the evidence used to originally convict Sion Jenkins was the presence of many small blood drops on Sion’s clothing (72 on his jacket, 76 on his trousers and 10 on his left shoe) [4].

There was a lot of ambiguity over how the blood got on to his clothing, as expirated blood usually implies that the person was still able to breathe when the blood was transferred to the object. In this case, that meant that Sion Jenkins was with Billie-Jo when she was still alive.

At the time of this case, there was very little, if any, research that had been performed on expirated blood, so both prosecution and defense needed to come up with plausible explanations as to how the blood got there.

Sion was acquitted of the murder in February 2006.

Since this case, more research has been published with regards to the analysis of expirated blood patterns, and their distinction from various other types of blood patterns. Expirated blood can be confused with both high and medium velocity impact spatter, and fly activity at the crime scene [3], so accurate analysis of the stains is crucial when determining the events involved with a crime.

Although more research has been done in this area, it is still a bit of an ‘unknown’ within the BPA territory, as only a couple of articles have been published.

References

[1] Power, D. A., Cordiner, S. J., Kieser, J. A., Tompkins, G. R. & Horswell, J. (2010) PCR - based detection of salivary bacteria as a marker of expirated blood, Science & Justice, 50, pp. 59 - 63.

[2] Silenieks, E. (2006) The detection of salivary amylase in expirated blood patterns, I.A.B.P.A News, June, pp. 5 - 9.

[3] Clark, K. (2006) Differentiating High Velocity Blood Spatter Patterns, Expirated Bloodstains, and Insect Activity, I.A.B.P.A News, September.

[4] Justice for Sion Jenkins. The Case of Sion Jenkins. Available at: http://www.justiceforsionjenkins.org.uk/maindoc.html (Accessed: 08.05.2012)