Colorado Criminal Sex Crimes Forensics: A Typical DNA Analysis in a Sexual Assault Case
What follows is a sample report, with the names redacted for confidentiality, of a Colorado Bureau of Investigations DNA Expert on sperm found at the scene of an alleged Sexual Assault – Date Rape. It is instructive in many ways.
Forensic Laboratory Examination Report
Agency: Colorado Springs Police Department
Reporting Section: Biological Sciences
Nature of Offense: SEX ASSAULT
Involved Subjects Suspect:
Agency Case #:
Investigated by:
Submitted by:
Date Reported:
Offense Code:
Results, Opinions and Interpretations:
A differential extraction was performed on Item 1 in an attempt 10 separate sperm cells and non-sperm cells. The DNA from each of these fractions was analyzed separately.
Microscopic examination of the sperm fraction of Item 1 revealed the presence of spermatozoa.
Deoxyribonucleic acid (DNA) was analyzed by Polymerase Chain Reaction (PCR) technology at the Profiler Plus / Cofiler loci for Items 2-1,3 and both the sperm and non-sperm fractions from Item 1.
The DNA profile developed from Item 1 (sperm fraction) matched the DNA profile from XXXX (Item 3). To a reasonable degree of scientific certainty and in the absence of an identical sibling, XXXX is the source of the DNA profile developed from Item 1 (sperm fraction).
The DNA profile developed from Item 1 (non-sperm fraction) revealed \he presence of a mixture. The major component of the mixture matched the DNA profile from CRYER (Item 2-1). To a reasonable degree of scientific certainly and In the absence of an identical sibling, XXXX is the source of the DNA profile developed from Item 1(non-i5perm fraction). XXXX (Item 3) cannot be excluded from contributing to the mixture at all loci.
The percentage of the population that can be excluded from contributing to the mbdure is approximately 99.9997%. The DNA profile from Item 1 (sperm fraction) qualifies for entry into the CODlS (Combined DNA Index System) database. Both state ami national seamhes will be performed on a routine basis. The investigating officer may be notified if any investigative leads are obtained.
Evidence Disposition:
The DNA packet win be kept frozen and may be stored at the CBI up to one year from the original date of submission. All other items will be returned to the submitting agency.
Remarks:
DNA (deoxyribonucleic acid) analysis utilizes polymerase chain reaction technology (PCR) to analyze short tandem repeats (STRs). It may also be used to analyze STRs on the Y chromosome (YSTRs). For partial profiles, only the loel used In the statistical calculation are listed. The remaining loci were either inconclusive or provided no results. Statistically inconclusive loci may stili be used for interpretation purposes. Amelogenin is not utilized in statistical calculations.
Examined by:
Barbara B Ray
Laboratory Agent/Criminalist
Biological Sciences