Touch DNA is a forensic method for analysing DNA left at the scene of a crime. It is called “touch DNA” because it only requires very small samples, for example, skin cells left on an object after it has been touched or handled. Touch DNA analysis only requires seven or eight cells from the outermost layer of human skin.(Wikipedia)
This relatively new forensic technique of using “touch DNA” is being employed in several countries to help solve those crimes which have previously been too difficult or impossible to solve. This new technique is mostly used for investigating property or high volume crimes and involves testing evidence such as an object or broken glass for “touch DNA” – microscopic skin cells containing DNA that naturally rub off when an object, such as a cell phone or steering wheel, is touched.
Even gloves don’t let them get away with it!
Touch DNA technology can even be used if the suspect was wearing gloves at the time of committing the crime because there’s a high likelihood that the skin cells were transferred onto the gloves when the perpetrator was putting them on. Property and other nonviolent crimes are often overlooked in South Africa due to the fact that no violence was involved or due to a lack of physical evidence. Or so it seems….. However, the SA Forensic Science Lab recognises that not only do criminals have a ‘career path’ which often starts with less serious crimes, but more violent criminals also dabble in other types of crimes, such as housebreaking. This is why they advocate for the use of Touch DNA in South Africa. The rationale behind collecting DNA from ‘volume’ crimes would be to include these DNA profiles onto a DNA database where the chance of a match to a known suspect would be increased.
This type of technology could be used effectively in hijackings as there will be a large number of physical clues left behind in a vehicle if employing ‘Touch DNA’ as a methodology to collect evidence from these types of crimes.
Collecting the best samples
In order to take advantage of touch DNA, it is also important for the CSI to collect the right samples. This technique can be used on samples taken from guns, steering wheels, cell phones, glass, plastic, wood, cloth, fabric, to name a few. It does however require discretion inso far as focusing on the places a suspect is likely to have touched. Eg, in the case of a hijacking, taking samples from the entire dashboard would not be prudent. Instead, the CSI should focus on processing the steering wheel; the door and the door handles; the rear view mirror; the gear stick; the controls for the windows, the stereo and the air conditioner.
If the crime scene is indoors, observe the scene. Did the suspect try to cover up by washing his hands? If so, tell the CSI to take samples from the faucet and sink surfaces. Look for bathroom or kitchen towels or discarded paper towels. (BUT DON’T TOUCH THEM!) Tell the CSI to remember to process the doors and windows that a suspect may have used to enter or exit the property/crime scene. Ensure that any clothing that may belong to the suspect is tested for touch DNA too. Finally, look for any items that are out of place—chances are, the suspect was the one who moved them!
If you are a non essential, non forensic person (in other words EVERYONE OTHER THAN A QUALIFIED CRIME SCENE INVETIGATOR!), keep out of the crime scene and take notes should you have observed anything which the CSI may be able to use to assist in his or her investigation of the crime scene.
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