Biological evidence in criminal investigations

CRIMINAL JUSTICE FORENSICS & DNA: PRESERVATION OF BIOLOGICAL EVIDENCE

The objective of this work is to report on the methods and tools for investigation in the area of biological evidence as it pertains to preservation of biological evidence and specifically through review of five articles on this subject.

Biological evidence is defined as "evidence that is commonly recovered from crime scenes in the form of hair, tissue, bones, teeth, blood, or other bodily fluids." (West Virginia University: The Basics of Biological Evidence, 2009) It is reported that there may be only one form of biological evidence at the scene of a crime however; there also may be multiple forms of biological evidence present. (Ibid) It is critically important that the physical evidence at the scene of a crime be properly collected and preserved. (Ladd and Ladd, 2001)

Collection and Preservation of Biological Evidence

The work of Catalin, Andrei, and Mitrasca (nd) entitled: "Modern Methods of Collection and Preservation of Biological Evidence for Human Identification by DNA Analysis" states that physical evidence has become "increasingly important in criminal investigations...during the past few decades." Factors that affect the ability for obtaining a DNA profile:

(1) The sensitivity of PCR DNA typing methods is still limited;

(2) Sample degradation; and (3) Sample purity and DNA content of different types of samples. (Catalin, Andrei, and Mitrasca, nd)

Since all biological evidence is "subject to deterioration" it is critical that biological evidence be carefully collected and stored in order to ensure that the evidence is preserved in a condition that it is possible to obtain useful information from the analysis of the evidence. (Catalin, Andrei, and Mitrasca, nd, paraphrased)

II. Collection of Blood

Blood collection should be conducted by qualified medical personnel. Collection involves taking two tubes of blood, approximately 5 mL and collecting the blood in vacutainers with EDTA as an anticoagulant. Next, the tubes should be labeled with the date, time, name of the subject, location, name of the collector, case number and exhibit number. Blood samples are then to be refrigerated and should not be frozen. Blood samples should be submitted to the laboratory as quickly as possible. (Catalin, Andrei, and Mitrasca, nd, paraphrased)

III. Bloodstains

It is reported that objects that are small and that bear wet bloodstains "should be allowed to air dry and then collected as is." (Catalin, Andrei, and Mitrasca, nd) There should be efforts made for preservation of the "integrity of any bloodstain patterns during packaging and transportation." (Catalin, Andrei, and Mitrasca, nd) In the case of large objects in which it is not feasible to move them from the crime scene the web blood should be transferred onto a clean cotton cloth. It is important to label each object and container properly. (Catalin, Andrei, and Mitrasca, nd, paraphrased)

IV. Documentation of Semen Evidence

Semen evidence should be documented through use of "notes, photography, videotape and sketching." (Catalin, Andrei, and Mitrasca, nd) It is reported that one should use a "clean syringe or disposable pipette to transfer liquid semen to a clean, sterile test tube." (Catalin, Andrei, and Mitrasca, nd) The tubes should then be labeled with the "case and item number, date, time, location, and name of the collector." (Catalin, Andrei, and Mitrasca, nd) The specimen should be refrigerated and sent to the laboratory as quickly as possible. Liquid semen may be "transferred onto a clean cotton cloth by absorption. The cloth is then air dried, packaged, sealed and labeled properly." (Catalin, Andrei, and Mitrasca, nd)

V. Importance of Preservation of Biological Evidence

The work of Jones (2005) entitled: "Evidence Destroyed, Innocence Lost: The Preservation of Biological Evidence Under Innocence Protection Statutes" reports that a pardon was issued to Kevin Byrd by Texas governor George W. Bush in 1997. Byrd had been convicted of the sexual assault of a pregnant woman. At the time that Byrd was tried in 1985 DNA technology was not capable of forensic analysis of biological evidence however; in 1997 a comparison was conducted of Byrd's DNA with the bodily fluid in the rape kit that had been collected at the time of the incident resulting in Byrd's exoneration for this crime. The importance of proper preservation of biological evidence is highlighted in this case and not only for the purpose of obtaining a conviction but also for the purpose of ensuring that the wrong individual is not charged, found guilty and sentenced to prison for a crime that they did not commit.

VI. Most Common Applications of Blood Evidence

The work of George Schiro entitled: "Collection and Preservation of Blood Evidence from Crime Scenes" states that prior to the documentation and collection of blood evidence the value of the evidence must be recognized by the crime scene investigator and "how it fits in the overall events associated with the crime." (nd) Schiro states that the most common applications of blood evidence are those as follows:

(1) Finding blood with the victim's genetic markers (ABO blood type, DNA profile, etc.) on the suspect, on something in the suspect's possession, or something associated with the suspect (such as the suspect's fingerprints);

(2) Finding blood with the suspect's genetic markers on the victim, on something in the victim s possession, or something associated with the victim; and (3) Investigative information determined from blood spatter and/or blood location. (Schiro, nd)

VII. The Mobile Evidence Preservation System (MEPS)