For many years, fingerprints evidence was the standard for investigating and linking suspects to a crime scene. Rapid evolution of forensic swabs and specimen collection has shaped DNA evidence as the gold standard.
However, it is important to consider that the effectiveness of forensic analysis depends on the quality of sample collection tools and methods. Low-quality sample collection, storage and transportation media can lead to potentially invalidated results.
Did you know?
Swabs have been critical to medical diagnostics since the early 1900s. You can see swabs haven’t changed much! It’s cotton attached to a handle, but today we have specialized swabs.
Harmony stocks more than 26 different types of foam swabs alone! But beyond biotechnology and median, static control requirements led to their use in manufacturing. Semiconductors require a range of static control protections like esd-safe swabs to prevent discharge when handled.
Forensic swabs are designed to collect DNA evidence and transport that evidence without specimen degradation.
Modern forensic swabs, made by Puritan Medical Products, have evolved since the early 1900s. The cotton is sterile, individually wrapped, and manufactured in a controlled environment. You may be familiar with sterilized cotton swabs already, but these are designed especially for specimen collection; the cotton is pharmaceutical grade!
How to swab for DNA evidence
At a crime scene, both physical evidence, such as a weapon, and biological evidence such as sweat or blood could yield DNA samples. If someone touched a weapon or object, various forms of touch DNA might have been left behind.
In case the crime scene provides a clear source of DNA, the sample can be collected using proven tools like swabs. Here is a simple process to swab for DNA evidence:
Preparation is the first step you should take to ensure effective DNA swabbing. Make sure your staff is well-trained and well-equipped. Approved personal protective equipment (PPE) such as gloves (and possibly even shoe covers, hair nets, and masks depending on the scene) must be used during DNA swab collection.
Proper preparation will help you avoid contamination of samples which can become a critical issue in court proceedings.
Swabbing is a preferred DNA sample collection method over taping. There are swabbing techniques used in accordance with the sample type (touch DNA, blood, sweat).
No matter the swabbing methods you implement, change gloves and forceps after each item is necessary to prevent cross contamination. Following are the three most popular techniques:
- Swabbing for touch DNA
- Double Swabbing for touch DNA
- Swabbing bodily fluids like blood
3. Preserving Forensic Swabs
One of the most important parts of collecting cells is ensuring that the swab is completely dry during preservation and transportation. Some of the modern collection tubes are designed to ensure both effectiveness and convenience in preserving samples.
Here are some tips that will help you conduct a reliable DNA evidence collection process:
- Wear protective gloves before removing the swab from its wrapper
- Touch only the handle of a forensic swab
- Pre-moisten the swab with sterile distilled water if the sample is dry
- Place the tip of the swab on the surface and rotate it gently to allow tissues to absorb into the fibers
- Put the swab tip-first into appropriate packaging and allow the sample to dry
Follow the pre-defined DNA collection procedures even if the crime scene has been compromised.
Use DNA-Controlled Swabs
When the job is to swab for evidence at crime scenes, you can choose from a number of techniques. But when it comes to DNA evidence collection, it is recommended to use DNA-controlled or DNA-free buccal swabs. Therefore, always use buccal or DNA swabs certified by an independent laboratory.
Following are two popular types of buccal swabs used widely at crime scenes:
- Flocked swabs are being increasingly used for forensic processes due to their unique structure which helps crime investigators collect, retain, and elute specimen better than other low-quality swabs. A flocked swab is also handy when it comes to collecting touch DNA from fingerprints or skin cells, or residue from arso, gunshots, or explosions.
- Sterile Cotton Swabs work for applications that do not depend on minimal samples. If the collection must be maximized, then flocked swabs are ideal.
Justin Hines is an author at Harmony Supply Blog. With over a decade of experience working with cleanrooms, controlled environments, and industrial manufacturers, Justin Hines provides content to Harmony Lab & Safety Supplies.