Currently in Michigan, the Michigan State Police Forensic Biology Unit conducts serology, which “may best be described as the examination of bulk evidence (swabs, fabric cuttings, tools, various weapons, sexual assault kits, clothing, masks, etc.) using a variety of microscopic, chemical, immunological, and enhancement techniques to locate and characterize bodily fluids,” including blood. Michigan State Police, Forensic Biology & DNA.1
In Michigan, blood-typing evidence, “like other pieces of physical evidence that show possible connections between defendants and criminal acts, [is] admissible, the weight to be given the evidence being subject to the jury’s determination.” People v Punga, 186 Mich App 671, 673 (1991). In Punga, 186 Mich App at 672, the Court of Appeals concluded that the trial court properly admitted blood-type evidence “indicating defendant was among thirty-four percent of the male population that could have produced the semen found on the victim’s clothing.” The Court explained:
“Evidence of blood type that places a defendant within a certain group of the population is relevant according to the definition of relevant evidence contained in MRE 401, in that it has some tendency to make the existence of a fact of consequence to the determination of the action more or less probable than it would be without the evidence.” Punga, 186 Mich App at 673.
“[F]rom eighty to eighty-five percent of the population are secretors, defined as persons who secrete their blood grouping within their body fluids. Nonsecretors do not secrete their blood grouping within their body fluids.” People v Trevino, 155 Mich App 10, 13 (1986).
Evidence of the defendant’s blood type and secretor status was properly admitted against the defendant at trial where “[p]hysical evidence overwhelmingly established that the child had been sexually abused and corroborated defendant’s identity as the perpetrator.” People v Hackney, 183 Mich App 516, 529 (1990). The Court explained:
“Sperm was detected on the child’s underpants and on paper towels discarded at the location of the sexual assault. Tests conducted on samples of the sperm indicated that the source, in all likelihood, was a secretor with an AB blood type, which is characteristic of only 3.2 percent of the fertile male population. Because the victim had type O blood, it was impossible that he could have been the source of the sperm. Tests done on samples of defendant’s blood and saliva indicated he was a type AB secretor.” Hackney, 183 Mich App at 529.
1 The link to this resource was created using Perma.cc and directs the reader to an archived record of the page. A detailed discussion of the scientific methods and definitions of terms relevant to the processes involved in forensic science is beyond the scope of this benchbook.