So What Did Margie Say About...CSI's Sexual Assault Kit

The 8/14/13 repeat episode of CSI: Crime Scene Investigation titled "Backfire" had its first blog entry on 4/11/13.

 

This time I'd like to talk about the Sexual Assault Kit that turned the investigation in this episode.  I haven't spoken of the contents of the kit prior to now.

 

The clothes are taken.  If not all of the clothes, the underwear in particular is taken at the very least.  The victim may be asked to remove her clothing while standing on a large sheet of paper so that any trace evidence that falls off during the disrobing may be collected and possibly used to help identify a perpetrator.

 

The fingernails are scraped, again to collect any possible trace or potential DNA from the suspect.

 

Wounds and injuries are photographed.

 

Swabs are taken and potential evidential fluids are obtained from the mouth, the anus, and the vaginal area.  Sometimes the inner thighs are swabbed as well. 

 

If the interview of the victim suggests that other areas are to be swabbed, then that area is swabbed as well.  For instance, the suspect may have kissed or licked the victim.  These areas need to be swabbed.  The suspect may have bitten the victim  These areas need to be swabbed and photographed and if bite marks are present, casts need to be taken.  And obviously, if the victim ejaculated on the victim or other object, these areas need attention. 

 

Hair samples used to be taken in the form of combings of the pubic region in case suspect hairs were present.  As I have mentioned in the past, microscopic examination of hairs is no longer routine and hairs that naturally fall out will not have the root present to get a DNA profile.  But if hairs from the suspect are pulled out - now there is the potential to have the root present and possibly a DNA profile from the suspect.

 

Times have changed over the last few decades and sexual assault victims are interviewed and treated differently than in the 'good ole days' when it was essentially up to the victim to prove that she didn't entice the perpetrator and wasn't just crying 'wolf'.  In the 70's and 80's the rape victim had to essentially have suffered severe injuries to obtain any credibility to her accusation of assault.

 

Thank goodness we are past that.  Unless, I guess, you are a drunk teenage girl who has overdone the beverage intake at a party attended by high school athletes.  But this is a topic for another day.

So What Did Margie Say About...CSI: Backfire

 

The 4/10/13 CSI: Crime Scene Investigation episode titled "Backfire" showed an excellent forensic evidence collection and preservation technique and one procedure that was, in my opinion, far from excellent.

The wrapping of the beaten female victim in a tarp led to the collection of the tarp.  If you noticed, they put paper strips over the tarp to protect the evidence.  You should baffle an article like a tarp, a bed sheet, clothing articles, etc. so that no two areas of the evidence touches itself when folding it for packaging and/or transportation to the laboratory.  This procedure protects a transfer of biological fluids, trace, or other materials from one area of the evidence article from coming into contact with another section during the folding.  In doing it like this, any information obtained can be more substantial when running an investigation or testifying in court.

The second procedure that I would like to discuss is the stringing reconstruction of the bloodstain patterns.  The first thing that a bloodstain pattern analyst would do would create a 'wagon wheel' 2-dimensional reconstruction that would show the impact site.  From here, one would use the stains which were used to find the hub of the wagon wheel through their directionality to measure their length and width to determine a mathematical formula to determine the angle at which a particular stain struck the 2-dimensional surface.  From here the procedure allows the analyst to follow the angle and tie it off to a perpendicular structure which had been placed at the 2-dimensional hub of the wagon wheel.  What you have as a result is a 3-dimensional area in space where the blood source underwent the trauma which caused the impact spatter to fly in the air and strike the surfaces where they landed.  There was nothing close to this in the mass of wild strings that they had apparently arbitrarily placed at the crime scene.  The only thing close to realistic was the use of different color strings to distinguish individual patterns.

How disappointing that they wouldn't take the time to properly display the technique which could actually give them the information that they commented on in the show: the location of the victims when they underwent the beatings.