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Do you believe that forensic serology or DNA analysis is more reliable when processing evidence in a criminal case? Explain your response.


                                                     CLASSMATE’ S POST 

First, I present support for my response by deferring to a statement gleaned from forensic scientists Saferstein and Roy’s work: Criminalistics: An Introduction to Forensic Science, (p. 401),In the United States, courts have overwhelmingly admitted DNA evidence and accepted the reliability of its scientific underpinnings” (Saferstein & Roy, 2021). The statement indicates the courts aligned with the quotation, thus in line with my answer. Another statement from Saferstein and Roy indicating a shift from serology analysis to DNA analysis is, “Before the advent of DNA typing, bloodstains linked to a source by A-B-O typing,” an approach now supplanted by the newer DNA technology the following (Saferstein & Roy, p. 396).

Further supporting the DNA testing reliability exceeding that of forensic serology, a comparison of DNA analysis and forensic serology analysis; thus, providing the additional support for my argument. The only negative in the reliability of DNA testing is the competency of testing personnel (Saferstein & Roy, 2021). Because DNA evidence is susceptible, crime scene personnel must be well trained in DNA preservation and handling. Some basic skills of DNA identifying, collecting, and packaging includes:

1. Identify- evidence at the crime scene relative to proving a linkage exists between the evidence, perpetrator, and the commission of a criminal act (FBI, 2021). Evidence was photographed and added to any sketch indicating a reference ruler for dimension scale (FBI, 2021). Evidence measured from reference points (e.g., walls or furniture to indicated on drawings the exact location found) (FBI, 2021).

2. Collect- and process biological evidence at property crime scenes to avoid contaminating the evidence (FBI, 2021).   Items collected must be dried before being sent to the laboratory. In gathering evidence, safety comes first. Any sharp object is packaged in an appropriate protection-designed evidence container of the package and labeled SHARP ITEM in bold lettering (FBI, 2021).  

3. Process- biological evidence at property crime scenes to avoid contaminating the evidence. Clothing items must be packaged in paper and identified with the case number, who collected the evidence, and the name of the suspect or victim, and the package must be sealed (FBI, 2021).   Rape evidence must be packaged in an approved “rape kit.” In the case of rape, the proof must be sent to a lab for processing within 72 hours of the incident, or consensual sex haven occurred—blood samples placed in purple sample test tubes (FBI, 2021).  The sample packaging is labeled with the donor’s name, the person who took the specimen, the date, and the time of collection. The DNA profile data is entered into the Combined DNA Index System (CODIS) if the laboratory participates in the national CODIS program (FBI, 2021).  

National Institute of Standards and Technology

    The National Institute of Standards and Technology (NIST) considers DNA analysis an extremely dependable process. Because most crime scenes contain large to minor amounts of biological material, DNA is often collected, preserved, and processed to render a genetic fingerprint (NIST, 2021).

Incompetence on Trial

    In Saferstein & Roy, a recollection of how a defense team “blew up” the prosecution’s case in California v. Simson in June of 1994. The DNA analysis of biological and physical evidence provided the suspect’s DNA co-mingled with two victim’s DNA collected from articles of the suspect’s clothing, crime scene, trial leading to the suspect’s vehicle, and the interior of the suspect’s vehicle. The defense team’s strategy was to display the forensic investigation team and accuse an initial responding detective of planting evidence (Saferstein & Roy, 2021). The trial was dubbed “Trial of the Century.” The center of the prosecution’s case was an abundance of physical, biological, and DNA evidence. Still, it would not matter because the competence of the actions at the crime scene in its processing and processing of the evidence created enough doubt in the jury’s mind to render adjudication of not guilty (Saferstein & Roy, 2021).

Serology versus DNA Analysis

    The two disciplines of serology and DNA analysis share kinship within the forensic community. Serology is a process in which evidence is sought in the bodily fluids of an individual, whereas DNA analysis aims to identify a specific person through examination of bodily fluids.      

Serology/DNA Analysis

    Serology analysis is the screening of crime scene evidentiary items before subjection to the DNA analysis (Mozayani & Noziglia, 2006). If it is suspected that bodily fluids are assumed to be present, then a serology/DNA analysis will be conducted (Mozayani & Noziglia, 2006).

Crime Scene Blood Identification

Luminal and Fluorescein Test

    Forensic scientist and authors of Serology and DNA Lisa A. Gefrides and Kathern E. Welch assert, one disadvantage to these tests is that both can have false-positive reactions Luminol and fluorescein will react with the same false positives as PH and with bleach and other cleaning fluids, which may interfere with blood detection on surfaces that have been cleaned. For this reason, fluorescein or Luminol positive areas should be retested with one of the color change presumptive tests. Another problem with the light-based tests is that they are typically used on very faint stains. Spraying a chemical onto an already weak stain may dilute the stain even further, which could lessen the chances of obtaining DNA from the sample (Gefrides & Welch, n.d., p. 1).

    In conclusion, although Serology and DNA analysis are closely linked, the most reliable of the two procedures. History was not so kind to law enforcement and laboratory testing personnel when in 1994, the “Trial of the Century” was lost due to the defense strategy of placing the crime scene process and the laboratory testing procedures under scrutiny. The case was ripe with both physical and forensic evidence and still managed to not convince a jury beyond a reasonable doubt about the guilt of the alleged suspect. 


National Institute of Standards and Technology. NIST Forensic Science. DNA and Biological Evidence. [website article].

    September 30, 2021.

Federal Bureau of Investigation. [Lab Services]. (October 1, 2021).

Gefrides, L.A. & Welch, K.E. (n.d.). Serology and DNA

Mozayani, A. & Noziglia C. (2006). The forensic laboratory handbook procedures and practice. Humana Press