Collecting Evidence from Sexual Assault Cases
Written by Dr. Kathy Gill-Hopple   

BEST PRACTICES have been identified by the National Institute of Justice (NIJ) and the Sexual Assault Forensic Evidence Reporting Working Group (SAFER) to assist jurisdictions and organizations working with evidence from sexual assault cases. These guidelines are intended to assist in the development of standardized practices for evidence collection, tracking, storage, submission, and analysis.

Healthcare providers, such as forensic nurses (FN) and sexual assault nurse examiners (SANE), frequently perform medical forensic exams, including evidence collection. Exams are conducted utilizing victim-centered care principles in order to promote collaboration between the victim and the nurse. Victim centered care focuses on the needs and concerns of a victim to ensure the nonjudgmental, compassionate, and sensitive delivery of services. During this process, the medical forensic examiner obtains the history of the assault which guides the collection of evidence. This occurs with consent of the victim. Many questions are asked about the assault, the actions of the assailant, and the hygiene activities of the victim after the assault. Questions are presented as a component of the medical and forensic history, not in an interrogating manner. A nurse experienced in victim-centered care principles recognizes the effects of trauma on the victim. It is not uncommon for victims to have memory lapses, disjointed memories, or to be completely unaware of the details of the assault. In these cases, the FN or SANE may collect a full range of samples.


Post-assault activities that may interfere with evidence preservation and collection must be recorded on the standardized medical forensic record, as DNA may be recovered from victims who have showered or bathed—even multiple times—after an assault. Even if the victim has bathed, vaginal swabs should be collected, as DNA has been recovered up to nine days after consensual intercourse (Speck & Ballentyne, 2014). Best-practice recommendations are to collect internal evidentiary swabs from the vagina up to five days (120 hours) post-assault, from the anus up to three days post-assault, and from the oral cavity within 24 hours of the assault. Consider carefully the potential for recovery of biological evidence even after a prolonged period of time.

General Guidelines

• Masks and gloves are to be used for collection of forensic evidence. The ever-increasing sensitivity of DNA technologies requires diligent attention to eliminate the possibility of cross-contamination.

• Effort must be made to concentrate collected foreign material on the fewest number of swabs necessary. Two swabs should be collected concurrently when possible. If not taken concurrently, they should be labeled with the order collected. The goal is to collect a CODIS-eligible DNA profile from the samples foreign to the victim. If a complete autosomal DNA profile is not available, partial DNA results or profiles from Y-STR profiles can be used.

• When collecting oral evidence, it is recommended to use two dry swabs, held together. Swab around the teeth, gums, and under the tongue. If there are tongue or lip piercings which the victim chooses to keep, swab underneath the piercing. Dentures may be removed and swabbed as well. If penile/oral penetration is suspected or reported, collection of oral samples should be completed and the victim should then be instructed to rinse the mouth.

Collecting an oral swab.

• Buccal samples are recommended as the standard way to obtain victim reference DNA. Two swabs are rubbed approximately 10 times on each side inside the buccal mucosa of each cheek. Swabs can be held together and used on both the right and left cheek.

• For anogenital evidence, two lightly moistened swabs, held together, are utilized to collect samples from the vaginal vestibule (labia minora, clitoris, hymen, fossa navicularis, and posterior fourchette). If genital piercings are present, pay particular attention to swabbing completely around the piercing insertion site; if the victim elects to remove the piercing, then be sure to swab the removed piercing over all surfaces as well as the piercing insertion site. The vaginal vault (including the cervix and posterior fornix) is swabbed with two dry swabs held together. Evidence from the penile shaft and glans (including under the foreskin and around the corona) and scrotum is swabbed with a total of two lightly moistened swabs. The anal folds and around the anal opening are also swabbed with two lightly moistened swabs (unless the history dictates otherwise, or the victim declines this collection). Rectal swabs are typically collected under circumstances necessitating an anoscope evaluation. If foreign materials and other wet evidence are retrieved from the vaginal vault during a medical forensic exam, these should be treated as potential reservoirs of foreign DNA. Dry the samples completely prior to packaging. When possible, package in a paper wrapper. Items that are too wet to be adequately dried should be clearly identified as wet, so local agency personnel can follow established protocols for drying.

• Limit the number of swabs for any given anatomical site to two, to avoid unnecessary dilution of the sample. Hold the swabs together and collect, while rotating the swabs to concentrate the foreign DNA.

• Slides and smears are no longer considered routine. Forensic labs which are moving to a Direct-to-DNA approach may perform sperm analysis on a case-by-case basis (SWGDAM, 2016).

• The same recommendations are followed for prepubescent children with an important exception: swabs collected from the vaginal vault are only collected when sedation or anesthesia is performed (Kenna et al, 2011).

• The underside of the fingernails are swabbed with a lightly moistened swab, one swab for each hand (to concentrate the sample). If the victim reports scratching the assailant, clippings are recommended rather than scrapings; scrapings may result in injury or infection to the victim. If the history indicates, the toenails are treated in the same manner as the fingernails. Label each swab separately as right or left, hand or foot.

Swabbing the underside of fingernails.

• Swab each hand with one lightly moistened swab over the entire palmar surface. Label as right or left, and package each separately, labeled as right or left palm.

• Only pubic hair, which can be combed, or clipped if matted, is to be collected. It is no longer considered appropriate to pull head or pubic hair from the victim. For victims without pubic hair, use two lightly moistened swabs over the mons pubis.

• Touch DNA can be recovered from the skin of the victim post-assault, particularly when a vigorous struggle has occurred. Salivary amylase (which does not contain DNA) has been retrieved from skin (with reports of kissing, licking, or biting). To collect, use lightly moistened swabs and double-sided adhesive tape pressed to areas indicated (Kenna et al, 2011). Wounds inflicted from bite or other oral contacts are swabbed with two lightly moistened swabs across the affected area.

Swabbing skin for touch DNA.

• The clothing in closest proximity to the potential evidence deposit should be collected. Typically, this is underwear, bras, or t-shirts.

The guidelines recommend not collecting urine and blood (unless used for toxicology). They also recommend not collecting emesis, flossing of teeth, nasal washes or flushes, plucked or pulled hair, and vaginal aspirates or washes as these are not considered standard samples. Potential health risks (such as infection) from flossing, rinses, or washes outweigh any benefit that may be derived from evidence collection. Foreign material may be forced into the nasal sinuses and iatrogenic injury may result from a forceful nasal wash. Vaginal washes may result in forcing foreign material further up into the reproductive tract—an ascending infection—which may have long-term effects on the victim’s reproductive health. There has been no research supporting the use of emesis for DNA analysis.

Often the question is what to collect when the victim cannot give a history. Each facility should have a policy addressing the samples to be collected during the medical forensic exam in the event that the victim is unable to provide a history. The following samples are recommended for evidence collection when a victim is unable to give a history of assault due to intoxication, loss of consciousness, or being under the temporary influence of drugs or alcohol:

o Peri-oral area, lips, oral cavity
o Neck
o Breasts
o Palms of hands and fingernails
o External anogenital structures
o Posterior fornix and cervix in the postpubertal female
o Peri-anal folds, anus, rectum
o Areas of alternate light source fluorescence
o Debris or foreign material gathered from the exterior or internal genitalia
o Urine and blood for toxicology
o DNA reference samples

Evidence from deceased victims should be collected when there is any suspicion of sexual assault or abuse, regardless of the state of decomposition. All potential sources of evidence should be collected which does include dental flossing, emesis, pulled scalp and pubic hair, swabs of the mouth, breast, external genitalia, vagina, cervix, and anus. In the case of the deceased victim, there is no risk of injury or infection from this collection.

The collection of evidence from a suspect requires the same attention to legal considerations as the collection of evidence from victims. When suspect exams are completed, it is best to have the medical forensic exam completed by a trained individual, in a different room than where the victim exam was completed. A different medical forensic examiner is also recommended, to avoid the possibility of cross-contamination. Specific procedures for cleaning the exam rooms, wearing and changing gloves, lab coats, wearing masks, and hand hygiene are important considerations for facilities where suspect exams are conducted. Buccal swabs are typically used for reference DNA samples, which can be collected by law enforcement agents. Any other samples should be collected only by a trained healthcare professional.

The record completed by the medical forensic examiner must include an inventory of all evidence collected, along with a narrative account of the recent consensual sexual activity, post-assault hygiene activities of the victim, date and time of the exam and the assault, the pertinent medical history of the patient, the nature of the assault, physical examination findings and any additional laboratory or diagnostic testing done at the time of the exam. Transfer of evidence while maintaining the chain of custody must also be recorded in the written documentation. The record should also include instructions for follow up, as well as information and instructions related to any medications administered.

Facilities must have written policies addressing retention of written and photographic documentation that either meets or exceeds the requirements of the criminal justice system. Issues related to delayed reporting or delayed processing of sexual assault evidence, cold cases and CODIS hits, and court appeals demand a higher level of attention, beyond the health information standards generally applied to medical records.

Systems utilized to electronically store sexual assault evidence collection records must be HIPAA compliant, but also allow for the retrieval and transfer of information to appropriate law enforcement agencies and prosecutors. Best practice includes processes for peer review and case review for quality assurance and improvement.

The NIJ recommends the development of standardized national guidelines for the examination, evidence collection, and documentation following a sexual assault using the minimum criteria from the National Protocol for Sexual Assault Medical Forensic Examinations - Adult/Adolescent, and the National Protocol for Sexual Abuse Medical Forensic Examinations – Pediatrics. Additional recommendations are included for evidence tracking, storage, submission, quality auditing, and laboratory analysis and processing.

About the Author

Kathy Gill-Hopple, PhD, RN, SANE-A, SANE-P, DF-AFN has been a forensic nurse for 18 years. She is the Chairperson of the Academy of Forensic Nursing Education Committee, and is the Coordinator of the Forensic Nursing Program at the Medical University of South Carolina. Dr. Gill-Hopple has been recognized as a leader in South Carolina, and has contributed to the state protocol for sexual assault, intimate partner violence, and human trafficking. She teaches multi-disciplinary SANE/SART trainings throughout South Carolina.


Kenna, J., M. Smyth, L. McKenna, C. Dockery, & S. D. McDermott, “The Recovery and Persistence of Salivary DNA on Human Skin,” Journal of Forensic Sciences. 56:1 (2011). Retrieved from:

Speck, P. & J. Ballentyne. “Post-coital DNA Recovery Study.” Retrieved from:

SWGDAM, “Recommendations for the efficient DNA processing of sexual assault kits.” (2016) Retrieved from:

U.S. Department of Justice, Office on Violence Against Women, “A National Protocol for Sexual Abuse Medical Forensic Examinations – Pediatric.” (2016) Retrieved from:

This article appeared in the Spring 2019 issue of Evidence Technology Magazine.
Click here to read the full issue.

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