Bloodstain pattern analysis is a helpful tool in the reconstruction of a crime scene. Bloodstain analysis gives the investigator the ability to de ants that could have occurred du ahe course of the bloodshed. Once es analysis is complete, these facts ar considered in light of all other evidence as a means of corroborating or refuting statements, confessions or investigative theories.
The information that can be discovered through careful bloodstain pattern analysis includes: the angle of the impact; the nature of the force involved in the bloodshed and the direction from which that force was applied; the nature of Jan object used in applying the force; the approximate number of blows struck during the incident and the relative position in the scene of the suspect, victim or other related objects during tIe incident.
Admissibility of Scientific Evidence
The trial judge who uses one of two tests decides the issue of admissibility of an expert's opinion testimony. The older of the tests is the general acceptance test that is based on Frye v. United States (293 F. 1013 (D.CC.Cir. 1923)).
"While courts will go a long way in admitting expert testimony deduced from a well recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs."
This language controlled the admissibility of scientific evidence for years; however, this test was heavily criticized. One of the arias that induced the most criticism was trying to determine which scientific field the particular technique belonged in. For example, bloodstain pattern analysis could belong in the field of crime scene investigation or reconstruction, yet it is based on the fields of physics, chemistry, biology and mathematics.
Courts applying the general acceptance test have usually held that bloo stain pattern analysis is sufficiently established to be admissible. For xample, in People v. Knox (459 N.E.2d 1077(1984)) the court held that the prosecutor could present expert testimony regarding bloodstain pattern analysis, stating that the testimony was based on a well-recognized principle and that general acceptance was established.
Often when this type of testimony is not considered to be sufficiently established it is because the proper foundation was not laid establishing the technique as a well-recognized scientific principle. In People v. Owens (508 N.E.2d 1088 (Ill.App.Ct. 1987)) the prosecutor failed to show that bloodstain pattern analysis had gained general acceptance and did not produce evidence to demonstrate the reliability of the evidence.
In 1975 the Federal Rules of Evidence were adopted, and 4 Rule 702 addressed scientific testimony. Rule 702 provides,
"If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify in the form of opinion or otherwise." (Fed. R. Evid. 702).
Under this rule, scientific evidence needs to be helpful, relevant and reliable. Bloodstain pattern analysis evidence was admitted pursuant to this new test of admissibility. In United States v. Mustafa (22 M.J. 165 (C.M.A. 1986)), expert testimony was permitted to enhance the government's theory of how the crime occurred. The court found that the bloodstain pattern analysis could assist the trier of fact to understand the evidence to determine a fact in issue; therefore, the agent could testify as an expert. The court even commented that Rule 702 was broader then the Frye test.
The Federal Rule of Evidence 702 seemed less stringent then the Frye test since the testimony only had to assist the trier of fact, but did not address the reliability of the actual scientific principle. The Supreme Court addressed this issue in Daubert v. …