| Literature DB >> 33843809 |
Julie L Valentine1, Paige Presler-Jur, Heather Mills, Suzanne Miles.
Abstract
ABSTRACT: Historically, evidence collection in sexual assault cases focused on obtaining foreign contributor bodily fluids through swab collection. With improvements in deoxyribonucleic acid (DNA) analysis methods, DNA profiles can be developed from touch DNA and applied to sexual assault cases. Following a literature review on factors affecting touch DNA transfer, a groping case study with innovative evidence collection is presented to support the expansion of touch DNA evidence collection in sexual assault cases. The groping case led to the development of a statewide sexual assault touch DNA form to guide evidence collection. DNA findings from additional groping sexual assault cases are reported to further show and justify the importance of evidence collection in groping cases. Implications on multidisciplinary practices are summarized to promote evidence collection and analysis in groping sexual assault cases. As forensic nurses are educated to accurately collect DNA evidence and provide trauma-informed, patient-centered care, they are best suited to provide nursing care for patients who have experienced groping sexual assaults. Optimal DNA findings in groping and sexual assault cases are best achieved through development of strong multidisciplinary, collaborative relationships between forensic nurses and forensic scientists.Entities:
Year: 2021 PMID: 33843809 PMCID: PMC8140663 DOI: 10.1097/JFN.0000000000000324
Source DB: PubMed Journal: J Forensic Nurs ISSN: 1556-3693 Impact factor: 1.175
Factors Affecting Touch DNA Transfer
| Factor | Implications on touch DNA transfer |
|---|---|
| Skin-shedding status | Profiles of high shedders: |
| Type of contact | Touch DNA yield increases with: |
| Substrate surface | Touch DNA yield is greater when collected from porous or rough surfaces (such as wood or fabric) than nonporous or smooth surfaces. |
DNA = deoxyribonucleic acid.
DNA Yield of Y-STR Analysis From Groping Case Study
| Swab location | Male DNA quant | Y-STR DNA profile development | Suspect part of mixture |
|---|---|---|---|
| Swabs collected by forensic scientists | |||
| Skirt | No male DNA | ||
| Jacket shoulders | Yes | More than three men | Yes, matches major portion |
| Tights | Yes | More than one man | Yes, matches major portion |
| Underwear | No male DNA | ||
| Swabs collected by SANEs | |||
| Lower abdomen | Yes | Yes, match to suspect | Yes, matches major portion |
| Underwear | Yes | Yes, match to suspect | Yes, matches major portion |
| Jacket button | No male DNA | ||
| Around mouth | Yes | Yes, low levels: match to suspect | Yes, matches major portion |
DNA = deoxyribonucleic acid; SANEs = sexual assault nurse examiners; STR = short tandem repeat; Y-STR = short tandem repeat on the Y-chromosome.
DNA Yield of STR DNA Analysis From Groping Case Study
| Swab location | DNA profile developed from foreign contributors | STR DNA profile development | Suspect part of mixture |
|---|---|---|---|
| Swabs collected by forensic scientists | |||
| Skirt | Not attempted | ||
| Jacket shoulders | Yes | More than two foreign contributors | No |
| Tights | Yes | More than one foreign contributor | No |
| Underwear | No male DNA | Not attempted | |
| Swabs collected by SANEs | |||
| Lower abdomen | Not attempted | ||
| Underwear | Yes | Yes | Yes |
| Jacket button | No male DNA | Not attempted | |
| Around patient's mouth | Not attempted | ||
DNA = deoxyribonucleic acid; SANEs = sexual assault nurse examiners; STR = short tandem repeat.
FIGURE 1Skin swab designation from a sexual assault examination form.
Sexual assault kits (SAKs) with full or partial STR DNA profiles from touch contact
| Suspect relationship | Swabs developing full or partial STR DNA profiles | Number of STR loci | CODIS entry | |
|---|---|---|---|---|
| SAK 1 | Initial meeting, online dating app | Vaginal, perianal, buttocks | Partial (not specified) | No |
| SAK 2 | Stranger | Vaginal | 15 loci | Yes |
| SAK 3 | Stranger | Perianal, rectal | 21 loci | No |
| SAK 4 | Stranger | Fingernails, neck and wrist | 16 loci | Yes |
| SAK 5 | Stranger | Face, neck | 12 loci | No |
| SAK 6 | Acquaintance | Vaginal, perianal | 21 loci | Yes |
CODIS = Combined DNA Index System; DNA = deoxyribonucleic acid; SANEs = sexual assault nurse examiners; STR = short tandem repeat.
Laboratory Workflow Steps in DNA Analysis
| Workflow step | Definition |
|---|---|
| Serology | Serology describes the use of physical and chemical methods to determine location and identification of bodily fluids such as blood, saliva, and semen. |
| DNA extraction | Extraction is the separation and removal of proteins and other cellular materials that are present in a biological sample from the DNA molecules. |
| Quantitation | Quantitation determines the quantities of human DNA present in the DNA extract. |
| Amplification | Polymerase chain reaction (PCR) is a process where a specific region of DNA is replicated over and over (amplified) to yield many copies of an otherwise small original amount of DNA. PCR targets specific locations, or loci, of interest on the DNA molecule that have been found to vary between individuals. |
| Separation and detection of DNA | The PCR products are separated according to size, visualized using a detection cell, and stored in an electronic format for later analysis. |
| Data review and troubleshooting | The analyst reviews all data produced in the previous step to ensure the results adhere to the basic criteria and interpretation guidelines developed by the laboratory. |
| Data interpretation | The sample profile is compared with a known sample profile to determine a match or an exclusion. |
DNA = deoxyribonucleic acid.