Sexual Assault Medical Forensic Examination Research Forum: Types of Evidence Gathered

The broad research questions posed to forum participants relative to this topic were: What is the impact of having specific types of evidence gathered on victims, the investigation, and likelihood of prosecution and conviction? How are exam findings used during the criminal justice process?

Norm Gahn, with the Milwaukee District Attorney’s Office, first presented a prosecutorial perspective on this topic. He and the participants raised the following questions (several of which are addressed again later in this report):

  • For examiners, what factors go into making decisions about collecting evidence? What samples are routinely collected? What is collected based on what victims tell or don’t tell examiners during the oral medical forensic history? What impact does the evidence collection kit have on what is collected?
  • What guidelines can help ensure examiner consistency in taking the oral history from patients as the first step in determining what evidence to gather? Guidelines are important, both generally and also in cases of alcohol- or drug-facilitated sexual assault, when the victim is incapacitated and may not be able to consent to the exam or evidence collection, or if the oral history is fragmented. How should examiners proceed when they do not have an oral history from the patient to guide the evidence collection process?
  • What is the extent of feedback between examiners and crime labs on evidence collected and what to collect and how to collect it? How could increased communication contribute to increased quality of evidence collection and its usefulness in a case?
  • What is a crime lab’s protocol for testing evidence in sexual assault cases? Why? For example, a lab may go straight to DNA testing rather than focus on identifying the biological substance.
  • What is the relationship between prosecutors and crime labs? A suggestion was made to track the history of interactions on cases between the lab and prosecution.
  • How often does the prosecutor ask the crime lab for additional testing? And why?
  • What is the linkage between DNA and the assault?[1] How much of an impact do DNA and other forensic evidence have on the prosecution in cases of nonstranger sexual assault? How often does DNA evidence help establish an element of the crime? For example, does it establish a sequence of events, corroborate statements of the victim, and/or verify or impeach a statement?
  • How do juries receive and react to forensic evidence? What is compelling? What is not? What is confusing? What might cloud the victim narrative and what supports it? How much does chain of custody of evidence/scientific evidence matter to jurors in consent cases?
  • Are injuries the most compelling evidence for law enforcement, for prosecution, for juries, and for victim? Several participants noted that injuries are compelling; however, there is not a hierarchy of what is the most important evidence in every case. In particular, prosecutors need further research and case law to establish the relevance of ano-genital micro-trauma/injuries in consent cases.

Specific Types of Evidence

Linda Ledray and Patricia Speck presented on this topic, looking at cervico-vaginal swabs and vulvar swabs; oral, anal, and skin swabs; debris; pubic hair; and toxicological samples in alcohol- and drug-facilitated sexual assault cases. With all types of evidence gathered during the SAMFE, there is a need for summative and formative program and process evaluation. Several participants indicated that examiner practices related to evidence collection were driven primarily by state crime labs via the sexual assault evidence collection kit. There were general questions that appeared to be applicable for each type of evidence:

  • What specific evidence is requested by the crime labs?
  • What is specifically recommended for inclusion in the evidence collection kit?
  • How long post-assault can the sample be collected and positive results be obtained when analyzed by the crime lab?
  • What is the decisionmaking process behind determining if a sample should be routinely collected or collected only if indicated (e.g., by the patient’s oral history and/or presence of injuries)?
  • What do examiners need to ask/tell patients to seek informed consent to collect a sample?
  • Where specifically are samples taken from, how are they collected, and how much of a sample/how many samples are collected? Why?
  • Which evidence collection techniques are the most patient-centered?
  • What collection methods help avoid contamination?
  • What can the attending medical providers and examiners do to preserve the evidence when life-saving actions for acute injuries must be taken?
  • What collection sites and methods produce probative evidence? The most? The least?
  • Is there a type of swab that is most effective in collecting samples (e.g., foam or cotton, plastic caps or boxes, paper or plastic tips)? Do samples have to be dried?
  • What is the most effective storage practice?
  • When and why is the sample sent to the lab for testing? How is the sample analyzed?
  • What is the impact of collection of the sample and method of collection on legal outcomes?

Some questions related to specific types of evidence:

  • Oral samples. Can chewing gum better collect oral specimens than swabs?
  • Anal samples. Several participants indicated that patients are often reluctant to talk about anal sexual activity, so there was a question of whether it should be collected routinely, or just as dictated by the oral history, or if there is injury in the ano-rectal area. It was noted that if the claim is anal intercourse, then an anal swab is needed as it would be probative evidence and corroborative. If the patient can’t recall what happened at all or the details of an assault (e.g., due to it being alcohol- or drug-facilitated), there might be reason to collect anal samples. Should anal samples be collected both from the anus and rectum?
  • Skin samples. Is a double swab technique (one moistened swab to loosen the cells, followed by a dry swab to collect the loosened cells) most effective for DNA analysis of a skin sample/touch evidence? Compared to using multiple swabs to the area? Compared to a stubbing method (tape-lifting)? What are crime labs requesting? What are examiners collecting? Are these samples analyzed differently?
  • Debris. Participants appeared to agree that the oral history should guide debris collection (as well as all other aspects of the exam). What constitutes debris? What materials will yield debris? What do examiners and law enforcement know about identifying/preserving debris evidence? If there are different methods for collecting different specimens, which produce probative evidence (fingernail swabbing, scraping, clipping, and/or cutting; hair taping, pulling, combing, cutting, and/or tweezing; grab marks, etc.)? What are the most victim-centered approaches? What is the impact of these different collection methods on prosecution outcomes and on victims?
  • Pubic Hair. Questions focused on determining whether the collection of pubic hair, particularly pulled versus cut samples, has value in producing probative evidence and on investigative/prosecutorial outcomes. Some state crime labs no longer require pulled pubic hair. How often is pubic hair analyzed by crime labs and then used in case investigation or prosecution? Are the outcomes to the case of pulling and/or cutting pubic hair worth the pain/discomfort it may cause victims? Even if research would indicate that pubic hair samples generally do not impact legal outcomes, are there circumstances in which it would be appropriate to collect pulled and/or cut pubic hair? Does it depend completely on the patient’s oral history? If not, what are other factors to consider?

Toxicological Evidence in Alcohol-/Drug-Facilitated Sexual Assault (A/DFSA). Participants estimated that alcohol and/or drugs are factors in at least 50 percent of sexual assault cases. What are the criteria for medical forensic care in these cases? Do jurisdictions have A/DFSA guidelines for evidence collection and documentation? What do they encompass? In addition to the above general questions applicable to all types of evidence, some questions relate specifically to toxicology evidence:

  • Are responding law enforcement officers being trained to collect the first available urine if the victim cannot wait to go to the bathroom until arrival at the exam site? A suggestion was made to look at lab and prosecutorial outcomes in communities where it is law enforcement procedure to collect versus those whose procedure is to wait until the victim gets to the exam site.
  • What is the timeframe after an A/DFSA that jurisdictions are collecting urine samples? The Society of Forensic Toxicologist (SOFT) currently recommends that urine be collected up to 120 hours after an A/DFSA. Given the SOFT time frame for collection of urine, there were two related questions: What drug/alcohol evidence is being lost in states that are not doing evidence collection beyond 72 and 96 hours after an incident? What is the impact of delayed reporting on A/DFSA cases?
  • Are toxicology samples routinely collected in cases where alcohol was involved in the assault? Is a gray top toxicology blood specimen routinely collected? Why? Why not?
  • Should examiners encourage victims to submit to toxicology evidence collection always and put it in the chain of evidence to analyze later if needed?
  • What are best practices in cases where the patient is incapacitated or unconscious due to alcohol and/or drugs and not able to provide informed consent to evidence collection? What is the appropriate level for informed consent needed to collect evidence in these cases (e.g., is waiting until all drugs/alcohol wear off required)? Participants noted that if a patient does not have a surrogate, evidence typically cannot be collected until there is a court order or a surrogate who can give permission. Some states have statutes that guide evidence collection in some of these situations (e.g., in the case of an unconscious patient).
  • What are hospital screening levels for toxicology, and when should examiners go beyond that screening with patients? For example, when alcohol and/or drugs are involved, medical providers may routinely take blood samples from patients to test blood/alcohol content and to determine if patients are capable of giving informed consent to an exam. If there is indication that drugs were ingested within 24 hours of the exam, they also may take a urine specimen as it may show more specifically when the drug was ingested and the effect of the drug on the individual.
  • Do examiners take toxicology samples for medical purposes separate from ones they take for forensic purposes? For example, in California, they do take separate samples when collecting for medical and forensic reasons.
  • What percentage of forensic results used during an investigation and/or prosecution are obtained from hospital labs versus crime labs? How often are forensic decisions based on hospital data?
  • Are there specific storage issues related to toxicology samples? SOFT suggests refrigeration of toxicology samples (within a reasonable amount of time, which means as soon as possible). [2]
  • How many jurisdictional crime labs have the capacity to do toxicology analysis? If they have a capacity, to what extent? For example, can they test for some drugs but not others?
  • What do examiners/law enforcement officers do in jurisdictions where the crime labs do not have this capacity? Or only test for certain drugs? How many are using commercial labs and how does this logistically work?
  • How extensive is the impact of alcohol and/or drugs on case outcomes? What are the specific problems with the evidence in those cases that are prejudiced by this evidence?
  • How many A/DFSA cases do not proceed in the criminal justice system because the victim has a drug problem or withdraws once she/he sees what she/he is up against? What about victim populations who do not come forward at all? Participants indicated that studies were needed to examine vulnerable populations, the impact of voluntary versus involuntary use of alcohol/drugs in these cases, and the impact of the criminal justice response on victims’ lives.

Next section: Examination Technology.


[1] Norm Gahn stressed that prosecutors need to first believe the victim’s account and then seek scientific evidence to back up that account. He stressed that DNA and other forensic evidence, where available, can be useful to build a case, in part because juries expect it (see next bullet).

[2]There was a question regarding why SOFT guidelines are not always included as crime and/or commercial lab procedures, despite the fact that the United Nations is mirroring SOFT’s guidelines. What needs to happen for jurisdictional and commercial labs to implement practices recommended by SOFT?

Date Created: September 13, 2012