Forensic Swabs For Crime Scene DNA Evidence

Advancing Swab Science

Forensic Swabbing

Throat swab used to diagnose diphtheria, England, 1901-1930
Puritan Sterile DNA Controlled Cotton Swab with Transport Tube P25-806-1PC-BT-FABUSA
Puritan Sterile DNA Controlled Cotton Swab with Transport Tube P25-806-1PC-BT-FABUSA used as a forensic swab and diagnostics.

For many years, fingerprints evidence was the standard for investigating and linking suspects to a crime scene. Rapid evaluation of forensic swabs science has shaped DNA evidence as the gold standard.

A few cells are all an investigation team needs to obtain in order to get enough DNA information to identify a suspect.

DNA analysis has been helping law enforcement agencies solve crimes for more than three decades.

DNA swabbing plays a critical role in streamlining crime scene investigation. They enable forensic professionals to extract valuable information from even the smallest samples of saliva, urine, blood, and other tissues.

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.

How to swab for DNA evidence

The collection of DNA evidence is a highly effective technique used worldwide to solve investigations.

It is essential for medical examiners, forensic scientists, and crime scene investigators to master DNA specimen collection methods.

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

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.

Sterile swabs, distilled water, transport media, evidence tape and flashlights are some of the essentials your evidence collection kits should contain.

Swabbing

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

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

There are several environmental factors such as temperature, mold, and bacteria that can affect the DNA at the crime scene.

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.

If the swab is not free of human contaminants like DNase and DNA, it could compromise the sample, and consequently, the case.

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

HydraFlock® Flocked Sterile Swab, Elongated Tip P25-3806-H-2
HydraFlock® Flocked Sterile Forensic Swab, Elongated Tip P25-3806-H-2

DNA-free flocked swabs are ideal when you have to deal with an extremely small sample size.

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.

Cotton Swabs

Puritan Cap-Shure Sterile Cotton Forensic Swab: 25-806-1WC-EC

If the sample is large enough and there is no need for advanced collection and elution, a sterile cotton swab, either with polystyrene or wooden handle, will do the job.

If it is not required to transfer the sample to FTA cards, it is recommended to use cotton swabs, not only for DNA collection but also for other medical applications.

About Harmony Business Supplies

Need a forensic swab supplier? Harmony can help. Get premium quality buccal swabs ideal for collecting DNA samples from crime scenes.

Forensic professionals have been relying on Harmony for our large collection of cost-effective swabbing solutions.

Available with cotton, flocked and foam tips, our forensic swabs are certified for forensic work and tested to the most stringent standards.

Visit our online store to learn more about our collection of forensic swabs.

5 Things You Didn’t Know About Swabs

1.     Homely Inspiration

The inventor of the modern cotton swab, Polish inventor Leo Gerstenzang, was inspired at home when he saw his wife sticking cotton balls onto the ends of toothpicks, and using this tool to clean out their child’s ears. Can you imagine doing that now? The original target audience for this new product was babies, and Q-Tips were first called “Baby Gays”.

2.     Boric Acid Baths

Original cotton Q-Tips were dipped in boric acid in the factory, as an idea to promote them as personal hygiene instruments. Boric acid has anti-viral and anti-fungal properties and sterilized the swabs.

3.     Stuck on Wood

Cotton swabs were made exclusively with wooden shafts until 1958. The company bought another company that made paper sticks for candy, and used the paper shafts in their swabs. Now, swabs are made with various shaft materials, including polypropylene shaft swabs, paper shaft swabs, aluminum shaft swabs, and others.

4.     Swabbing Sailors

A swab is a piece of absorbent material on end of a shaft/stick.

Did you know the word swab comes from the 17th mid-century “swabber”, in the sense of a sailor swabbing the deck of a ship. Why did they even swab the decks? Well, loose gun powder on gun-decks (cannons!) was a significant fire hazard. Swabbing the decks with a mop (swab) dampened the powder and reduced fire risk. Regular maintenance of the decks also slowed decomposition and gave sailors something to do. (Idle hands lead to mutiny!)

5.     All Ears (But Not Really)

Cotton swabs are widely known for being used to clean out ears. However, using swabs to clean the INSIDE of your ears can actually have an opposite and detrimental effect. Improper usage can lead to compacting wax or damaging sensitive ear organs caused by pushing the swab into the ear too far. Be cautious when using swabs to clean out ears.

 

Nowadays swabs are super useful across many different fields! Swabs of various kinds are used in critical environment manufacturing, diagnostics, environmental surface sampling, food safety testing, forensics, healthcare, and pharmaceutical applications.

Modern swabs are made tough to scrub hard to reach places, or soft and gentle for use in electronics or sensitive components. Hopefully you learned something new about swabs (who knew!), and whatever your application is, we have the swab for the job.

Forensic Swabs

Updated 12/1/16

No field requires as much precision as in forensic investigations. The data collected is a major factor in investigations, and how the data is collected plays a role in the accuracy of that data. DNA-Free and RNase-Free Forensic Swabs must cleanly and accurately collect samples while being certified DNA free and 100% sterile to avoid any cross contamination. Swabs are usually individually wrapped to stay fresh and to easily be transported after collection.

Forensic professionals rely on high quality swabs for clean and accurate sampling. Our collection forensic sampling swabs have been independently certified to be DNA-free at a threshold lower than any other swabs on the market today.

There are different types of DNA free forensic swabs to choose from, each with different specific focuses. Each swab features a soft, smooth, and absorbent tip. The swabs are manufactured to be medical grade and are ideal for crime scene investigations, buccal cell collection, and general specimen collection.

Foam tipped swab:

  • Large surface area for maximum cell collection
  • Ideal for swabbing the inner cheek and all buccal cell collection

Ultra Flocked Swab:

  • Unique fiber structure is designed for maximum cell yield
  • Ideal for conditions in which sample size is limited

Cotton Tipped Swab:

  • Manufactured with U.S. Pharmacopeial Convention (USP) grade cotton
  • Ideal for collection blood and buccal collection
  • A true multi-purpose forensic swab

We have a wide selection and sometimes picking out the right swab for the job can be a little challenging. If you have any questions about what swab is right for your application, please reach out to us and our product experts will be glad to help you!

Harmony Business Supplies

Swabbing For Trace Evidence VS Swabbing For Fluids

evidence and fluid swabbing

When it comes to sample collection there are two very different types. One is swabbing for blood or bodily fluids, the other is collecting trace evidence. It is important to note that while collecting fluid almost always involves using  a swab on  a visible portion piece of evidence, collecting trace evidence isn’t  always that straight forward. In this context, we must discuss forensic swabs.

 

Forensic Swabs

When it comes to trace evidence, methods of collection may involve the use of several other tools such as tape, sterilized needle-nose tweezers and dry transport systems. The swab comes in handy when collecting touch DNA from skin cells, fingerprints, or gunshot residue as well as explosions, arson.

 

Trace evidence with a swab is still different from when a swab is used to collect blood, semen and other bodily fluids.

 

Choosing The Right Kind of Swab

When choosing the right kind of swab, it is strongly suggested to choose DNA-Controlled Swabs.

These are swabs that are most specifically labeled DNA-Free Swabs or DNA-controlled. This translates to these being absolutely free of any human contaminants like DNA, DNase, and RNase which would compromise the sample. Always choose DNA-Free Swabs.

 

Among DNA-Controlled Swabs, the DNA-controlled flocked swab has proved to be popular because of its its unique micro structure. This micro structure makes it a better alternative to the standard cotton swab. Basically,  DNA controlled flocked swab by virtue of its structure can collect, retain and elute specimen the best. This makes it perfect for PCR, molecular assays, DNA testing and direct antigen testing.

 

However, this does not meant that the DNA- controlled cotton tipped swab in unacceptable. In cases where a large sample is needed and advance collection and elution needs are not there, a sterile and DNA controlled cotton tipped swab with a wooden or polystyrene handle is quite acceptable.

 

When DNA collection at a crime scene is undertaken, a comparison sample is a must. This helps in elimination of suspects leading to ultimate identification.. This is achieved by drawing the sample from the buccal cells from inside the cheek. This is buccal cell collection. It is recommended that foam tipped or cotton tipped swabs are used for this type of cell collection.

For instance, if the sample has to be moved to FTA cards, a large, round foam-tipped swab is ideal. With an extra large tip, this swab type provides extra surface area for maximum sample collection and preservation and minimizes discomfort. Alternatively if there is no requirement to transfer the sample to FTA cards, the sterile medical grade cotton swab with its own dry transport tube is perfect.

 

When it comes to trace evidence such as gunshot residue or touch DNA, sample size and sample type determines the decision on type of swab. For small samples the flocked swab with its unique precision and absorption capabilities come in handy and for large samples foam swabs work best.

 

The above thus covers most on forensic swabs and is sure to help choose the best swab for the requirement.

 

Shop our quality selection of Forensic Swabs and Sterile Swabs.

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