The Process of DNA Collection

Introduction 

The admissibility of scientific evidence in criminal cases depends on the evidence provided and whether it approves or disapproves a fact which may be useful in the findings of the case. Additionally, the expert presenting the evidence should be qualified and the information used should also meet acceptable procedures (Woody et al., 2007). DNA evidence plays an important role in criminal cases as it is used to charge the guilty and to free the wrongly accused. Since DNA evidence is a powerful tool during the investigation, it is important that all the involved parties should understand the process of DNA collection and how it is used in the courtroom. Every individual has got a unique DNA since its building blocks are different in the regions of every cell. 

The order of DNA building blocks is usually different in the various cell regions hence making each person’s DNA unique. For this reason, DNA sample generated from a crime scene can be used to link one to the incident under investigation or to eliminate an individual from being suspected (Hopwood et al., 2010). Before performing DNA test on a sample, the sample is collected and isolated and put in a good format for characterization. If that particular sample is not properly handled in the initial investigation stages, then no accurate results can be achieved, and no amount of work can compensate that in the later stages. The collection of DNA sample should be carefully conducted to produce DNA profiles which are acceptable in court and which are meaningful to the investigation. 

Types of DNA Samples 

There are different types of DNA samples. First, there are unknown samples which are recovered from the scene of the crime. Second, there are elimination samples recovered from a family member of the victims or even the victim themselves who are legitimately allowed to access the crime scene. Third, there are biological materials which are abandoned by any individual who is known to the law enforcement officers. The last category is any material which is discarded around the crime scene and which is retrieved by the authorities. 

Evidence Collection and Preservation 

One of the commonly used methods of evidence collection is the use of the double swab in which both wet swab and dry swab are used (Hopwood et al., 2010). The wet swab is usually moistened by getting it dipped in water and then brushing it over a surface to make loose cells which are present. The second dry swab is then used to collect any additional cell which may be present on the surface. Since the two swabs are used on a similar sample, both of them are combined to optimize the harvest of cellular materials collected. 

Another technique used to recover cellular material is by using adhesive tape which is either attached to plastic or acetate support. The tape is continuously pressed over an area with cellular material. The tape is then placed directly into the tube to realize maximum yield. (Walker et al., 1999). Tape lifting allows for the samples to be examined for the trace of evidence before being extracted for DNA. Some of the materials which may contain the DNA samples include the following: Dirty laundry, weapons, hats, clothing, tools, sexual assault evidence kits, underclothes, bedding, toothpicks, cigarette, toothbrush, eyeglasses, hairbrush, stamps, condoms or even tapes. 

How DNA is processed in the Field versus Laboratory 

To conduct comparative testing with pieces of evidence retrieved from a scene of a crime, either the biological samples are recovered from suspects, or the DNA profile evidence is cross-checked against the already existing database of the likely suspects. The sample references from family may be used in cases of missing persons, paternity testing and victim identification in a mass disaster. 

Bode Technology Group has come up with a Buccal DNA Collector which is used directly in collecting samples of buccal cells (Hopwood et al., 2010). This system of sample collection has its transport couch with a desiccant which helps in keeping the obtained samples dry. The system also contains a barcode on the DNA collectors which allows for automatic back checking of the samples. A toothbrush is also a good tool which can be used in collecting of the buccal cells. The cells are collected by rubbing the toothbrush inside the cheek and then tapping on the surface for sample storage and preservation (Verdon et al., 2014). 

Once the DNA samples have been obtained, they are taken to the laboratory to undergo the following stages; 

Extraction 

In this process, the DNA is released from the cells. 

Quantification 

In this process, the expert determines how much of DNA is retrieved. 

Amplification 

In this process, various copies of DNA are produced in order to help in characterization. 

Separation 

This is a process in which DNA product is separated to enable identification. 

Analysis and Interpretation 

This is the process involving comparing the DNA evidence to the already existing DNA profiles. 

Quality Assurance 

In this process, the analyst report is reviewed to establish technical accuracy. 

How DNA Sample can be compromised during Collection 

Contamination during Collection 

Contamination of DNA samples can happen in so many ways out of improper practices by the authorities handling the investigation. When the authorities fail to wear gloves when gathering evidence, then they can contaminate the evidence with their hands (Ballou, 2010). Evidence can also be destroyed when unauthorized people are allowed to get to the crime scene. Unauthorized people can tamper with the evidence by touching and stepping on them. The authorities can also interfere with evidence by sneezing or by rubbing the eyes. 

Exposure to direct Sunlight, Heat or Water 

DNA evidence may be compromised when it is directly exposed to extreme heat, water or direct sunlight (Ballou, 2010). It is important to collect and store evidence appropriately. Moisture can destroy the evidence and make it unreliable. DNA samples should not be stored in plastic bags because they can retain moisture. Evidence can also be tainted when it is left in a hot and poorly ventilated room. 

Crime Lab Errors 

The laboratories are not free from contamination. When employees forgo the basic rules by not wearing gloves, lab coats or goggles or even if unauthorized persons gain access to the laboratory then the results evidence can be compromised. 

DNA Evidence after Trials 

The evidence gotten from DNA is powerful not just during the trial but also after conviction. Prosecutors and the defense sides use the evidence gotten from DNA analysis to either prove that the defendant is guilty or innocent. The analysis of DNA can be used to free the wrongly convicted victims or even to convict the offenders. After analysis of the DNA results, the findings are recorded and uploaded in the national data in case of any reference (Walker et al., 1999). The evidence used is usually preserved for future references. Three types of results can be gotten from the testing. They include inclusion, exclusion or inconclusive results (Verdon et al., 2014) 

Inclusion 

This happens in a case where DNA pieces of evidence of a known individual either victim or suspect match the DNA evidence that is retrieved from the crime scene. If this happens to be the case, then the individual gets to be included as a prime source of that particular evidence. Even so, the depth of inclusion relies on the number of DNA locations examined (Verdon et al., 2014). 

Exclusion 

This is when the DNA profile of a suspect or the victim does not match the generated DNA profile retrieved from the evidence of the crime scene (Walker et al., 1999). If this is the case, then the suspect or victim is excluded as the prime source of the evidence. Sometimes, an extra investigation is done to establish the source of the evidence 

Inconclusive Results 

This is when the DNA testing does not produce any information which would enable an individual to be either excluded or included as the prime source of the evidence (Walker et al., 1999). Inconclusive results may happen when the quantity or the quality of the evidence collected is not sufficient to give definitive results. 

Primary Responsibilities of the D.A’s office 

The primary responsibilities that the D.A.’s office should adhere to include ensuring that they comply with the ethical rules as well as criminal procedures. To ensure adherence to compliance procedures, they should ensure that they work closely with the crime laboratory to coordinate the responses in the discovery process (Medwed & Daniel, 2009). For compliance with the ethical rules, the authorities should ensure that they accurately preserve any evidence that may add value to the case. These two responsibilities are important to realize justice for the victims (Medwed & Daniel, 2009). 

Types of DNA Tests 

The Y line DNA 

This is a test on the Y chromosome normally passed across the paternal line. Only the men can test for this since they are the only ones with the Y chromosomes. Here, the Y Chromosomes are compared to determine whether they match within a genealogical timeframe (Horvath, 2013). 

Mitochondria DNA 

This is normally passed from the mother to her children of both genders. This is usually passed only by the females. Males carry this DNA but are unable to pass it on. In this test, the mutations are compared to determine whether people share an ancestor within a particular period (Horvath, 2013). 

Autosomal DNA 

These are tests in which the rest of DNA is provided by both parent and not just on Y line or mitochondria DNA. This test usually provides a list of cousins from the individual’s line, but it is up to the individual to know how the cousins are related to him or her (Horvath, 2013). 

Emerging Technologies associated with DNA application 

There are numerous applications as well as research interest in the discovering the DNA technology. These include comparative genomics and evolution, sequence variation studies and diagnostic and applied therapeutics (Heller, 2002). There are more emerging technologies which promise solutions for affordable and fast genome sequencing. 

Recent Advances in Sanger Sequencing 

Microfluidic Separation Platforms 

The development of technology remains active for the approach of fluorescence-based Sanger in which emphasis is put on producing cheaper and faster sequencing reads (Woody et al., 2007). Application of microfluidic separation devices is one key area of research. The devices can be fabricated by substrate materials with various processes of molecular biology integrated on one device. 

References 

Ballou, S. (Ed.). (2010).  Electronic crime scene investigation: A guide for first responders . Diane Publishing. 

Heller, M. J. (2002). DNA microarray technology: devices, systems, and applications.  Annual review of biomedical engineering ,  4 (1), 129-153. 

Hopwood, A. J., Hurth, C., Yang, J., Cai, Z., Moran, N., Lee-Edghill, J. G., ... & McAlister, C. R. (2010). Integrated microfluidic system for rapid forensic DNA analysis: sample collection to DNA profile.  Analytical chemistry ,  82 (16), 6991-6999. 

Horvath, S. (2013). DNA methylation age of human tissues and cell types.  Genome biology ,  14 (10), 3156. 

Medwed. Daniel S. (2009). The Prosecutor as Minister of Justice: Preaching to the Unconverted from the Post-Conviction Pulpit.  Wash. L. Rev. ,  84 , 35. 

Verdon, T. J., Mitchell, R. J., & Oorschot, R. A. (2014). Swabs as DNA collection devices for sampling different biological materials from different substrates.  Journal of forensic sciences ,  59 (4), 1080-1089. 

Walker, A. H., Najarian, D., White, D. L., Jaffe, J. F., Kanetsky, P. A., & Rebbeck, T. R. (1999). Collection of genomic DNA by buccal swabs for polymerase chain reaction-based biomarker assays.  Environmental health perspectives ,  107 (7), 517. 

Woody, S. T., Austin-Phillips, S., Amasino, R. M., & Krysan, P. J. (2007). The WiscDsLox T-DNA collection: an Arabidopsis community resource generated by using an improved high-throughput T-DNA sequencing pipeline.  Journal of plant research ,  120 (1), 157-165.