10.3: Collecting specimen
- Page ID
- 53441
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)The one thing that is often neglected while processing the blood-letting event crime scene is the proper collection of specimen swabs for presumptive testing and laboratory analysis. Obviously, there will come a time either during analysis or when testifying in court that the question of who bled where will need to be resolved. Because of this, it is imperative that bloodstains must be swabbed and sampled. This is actually a very easy process, but it must be done properly. Step one is to don PPE’s including an N-95 mask and gloves. Your author uses sterile 100% cotton-tipped wood applicator swabs that are in sterile packaging, like those found in a medical office. Prior to opening the swab envelope, your author uses a soft-tipped pen to write the important case information on the exterior of the envelope. Your author then carefully opens the envelope at the stick end (not the cotton end). Your author carefully pushes both applicators out of the envelope just far enough to slide an applicator collar on the end of each applicator. He then pushes the collars up to the middle of the envelope and then draws both applicators out of the envelope together, being very careful not to touch anything as he removes them from the envelope. Retain the envelope because you are going to use it again. If the blood being collected is dry, you will need to apply sterile water to the applicator tip. Be sure to use a sterile water ampoule and never touch the tip of the cotton swab with the tip of the ampoule. Instead, drop the water from a height of about one inch. If the blood is wet, you may disregard the need for sterile water. Dab the applicator tip into the blood, being sure not to collect from the periphery of the stain, or from the clotted center. Slide the collar up over the cotton tip, break off about 1/3rd of the remaining stick from the bottom, and carefully place the swabs back into the sterile envelope with the collar and cotton tip near the opening (stick end first). Be sure to air-dry the swabs before sealing the envelope with evidence tape. It is very important for the swabs to be dry before sealing the envelope for long-term evidence storage. If the blood specimen has dried to the point of flaking, you can use the above wet method or scrape the flaked blood into a coin envelope. Be sure to wear safety goggles whenever handling flaked blood as blood-borne pathogens may become airborne.
Note that it is not necessary to use the plastic collars when collecting blood swabs for presumptive testing, as you will likely sacrifice the swab during the testing process. Your author uses swab collars that are open on both ends (one small opening and one large opening). The open-ended collar allows for faster drying. Furthermore, it is imperative that you swab one stain at a time. This will prevent placing the wrong swab in the wrong envelope.
Finally, it is important to examine the suspect, and suspect clothing, of a blood-letting crime for signs of blood spatter. Document the discovery with photography and swab the stains in the manner explained above.
