Condom trace evidence: a new factor in sexual assault investigations.

In an age filled with potentially fatal sexually transmitted diseases, more and more individuals practice safe sex. Even perpetrators of sex crimes have begun to wear condoms.(1) It is not likely that a fear of disease prompts this behavior. Rather, just as a burglar dons gloves to avoid leaving fingerprints, sexual offenders now wear condoms to avoid depositing seminal fluids.

Forensic experts typically identify sexual assault offenders by examining seminal fluid residues for sperm, proteins, blood grouping factors, and DNA profile. When sexual assailants use condoms, however, assuming no leaks or spills, this valuable evidence gets trapped inside the condom, which investigators may never recover. The same can be said for any traces from the victim including vaginal cells, blood, and saliva - that otherwise might have been transferred to the assailant's penis. Nevertheless, when assailants use condoms, they leave behind other valuable evidence.

TYPES OF CONDOM TRACE EVIDENCE

Manufacturers produce condoms using a variety of materials, both natural and synthetic. Each manufacturer has its own formula, which may vary even among its different brands.

Some condoms are made from lamb membranes, and one manufacturer recently introduced a model made from polyurethane plastic. Still, latex rubber condoms have, by far, the largest share of the market, perhaps because they cost considerably less. In addition to the basic materials they use to produce condoms, manufacturers also add other substances, known as exchangeable traces, which comprise particulates, lubricants, and spermicide.

Particulates

Condom manufacturers add finely powdered particulates to prevent a rolled-up latex condom from sticking to itself. Particulates found in different brands include corn starch, potato starch, lycopodium (a powder found in plants), as well as amorphous silica, talc, or other minerals. In the laboratory, forensic scientists use several different techniques to characterize these particles and compare them with those obtained from other condom brands.

Lubricants

Sexual assailants prefer lubricated condoms, probably for the same reason that they use petroleum jelly, that is, to facilitate their crimes.(2) Many condom brands con-rain a liquid lubricant, which may be classified as either "wet" or "dry."

Both types of condom lubricant have an oil-like consistency, but wet lubricants are water-based and/or water-soluble, while dry lubricants are not. Although many different manufacturers use the same dry lubricant, their viscosity grades sometimes differ. The forensic laboratory can recover these silicone oils easily from items of evidence and possibly associate them with a condom manufacturer.

Wet lubricants may contain either polyethylene glycol or a gel made from a combination of ingredients similar to those found in vaginal lubricants. Despite similarities to other products on the market, forensic examination can associate specific formulations with particular condom brands.

Spermicide

Both wet- and dry-lubricated condoms also may contain the spermicide nonoxynol-9. Its recovery and detection, along with lubricant ingredients and particulates, can help show condom use and indicate the specific brand.

THE VALUE OF CONDOM TRACE EVIDENCE

Condom trace evidence can assist investigators in several ways. It can help prove corpus delicti, provide evidence of penetration, produce associative evidence, and link the acts of serial rapists.

In Proving Corpus Delicti

Traces associated with condoms can help prove corpus delicti, the fact that a crime has occurred. This evidence can support the claims of either the victim or the accused. For example, the U.S. military can prosecute personnel diagnosed as HIV-positive for aggravated assault if they engage in unprotected sex, even if it is consensual. If service men accused of aggravated assault claim that they did in fact wear a condom but it broke or slipped off, condom trace evidence can support that claim.

In Providing Evidence of Penetration

Condom traces found inside a victim can provide evidence of penetration. In many jurisdictions, this evidence raises the charge to a higher degree of sexual assault.

In Producing Associative Evidence

Recovered condom traces may correspond to those found in a certain brand or used by a certain manufacturer. An empty packet of this particular brand found near the crime scene, especially if it bears the suspect's fingerprints, provides a strong association between the suspect and the crime. Unopened condom packages of this same brand found on the suspect, in his car, or at his residence also would help tie the suspect to the crime.

In Linking the Acts of Serial Rapists

People tend to be creatures of habit, and sexual criminals are no exception. A serial rapist likely will use the same brand of condom to commit repeated acts. Moreover, repeat offenders whose DNA profiles have been stored in a computer data bank may be likely to use a condom when committing subsequent crimes. Along with other aspects of his modus operandi, traces from the same condom brand or manufacturer found during several different investigations can help connect a suspect to an entire series of assaults.

GUIDELINES FOR EVIDENCE COLLECTION

Investigators need not make any drastic changes in their usual procedures in order to include the possibility of condom trace evidence. The following guidelines will assist criminal investigators and medical examiners when collecting this valuable evidence.(3)

At the Crime Scene

First and foremost, investigators must wear powder-free gloves to protect themselves from bloodborne pathogens and to avoid leaving particulates that may be similar to those contained in some condom brands. After collecting the evidence, they should package the gloves separately and submit them with the evidence so that the forensic laboratory can verify that the gloves did not leave behind any particulates.

At the crime scene, investigators should make every effort to locate any used condom and its foil package. If a condom is recovered, the traces from the victim on the outside and the seminal fluids from the assailant on the inside would have the greatest evidentiary value.

If investigators find an empty condom packet, they first should try to recover any latent prints from the outside. The inside of the package probably will not contain prints, but may contain lubricant, spermicide, and particulate residues. Investigators should wipe the inside with a clean cotton swab. The traces on this swab will serve as the standard for comparison with traces recovered from the victim and the suspect.

During Medical Examinations

Examination Kits

Most commercial sexual assault examination kits provide two cotton swabs for each type of examination, i.e., vaginal, penile, etc. In the past, before assailants began using condoms frequently, these two swabs proved adequate - one swab for immediate examination and a second in case the defense team requested another examination by its own experts or by an independent laboratory. With sexual offender's using condoms, however, forensic laboratories should use three swabs: One to save for the defense and two to conduct examinations.

With the potential for positively identifying a suspect, most laboratories first look for traces of seminal fluids, vaginal cells, blood, and the like. Unfortunately, the solvents used to conduct this examination also remove any condom traces present, thus losing potentially valuable evidence. Although examiners feasibly could divide each swab in half, providing an additional swab in kits for each condom trace examination easily could solve the problem.

The gloves provided in commercial examination kits usually come powder-free. However, the medical personnel who examine sexual offenders and their victims frequently prefer the gloves they normally wear, which often contain the same powders (corn starch, amorphous silica, and talc) found on many condom brands. While medical staff members may insist that their collection procedures are above reproach, forensic examiners cannot guarantee the integrity of the condom trace evidence if the medical staff wears their own gloves. In short, investigators must persuade examining personnel to wear unpowdered gloves.

After the medical examinations, investigators should recover and separately package the used gloves. The forensic laboratory then can confirm that the gloves were powder-free.

Examination of Victims

Victims of sexual assault may feel ashamed and may not want to disclose some of the more personal details of the crime. Although investigators should make every effort to spare victims any unnecessary discomfort or embarrassment, they must ensure a thorough investigation. This may mean asking victims embarrassing questions and then making sure that medical examiners obtain samples from any area of the victim's body where evidence may exist, including the vagina, the mouth, and the anus.

In addition to collecting traces from inside the victim's vagina, medical examiners should swab the external genitalia. Traces of water-soluble condom lubricants may have been absorbed or lost, and as a result, any traces found internally may be at a very low level. Thus, if the victim has not showered or bathed, swabs may recover undiluted traces present on the external genitalia. Although these traces would not indicate penetration, they at least would support the victim's assertion that sexual contact took place.

Moistening each swab with a few drops of isopropyl alcohol helps recover traces from external genitalia. To create control swabs for the forensic laboratory, investigators should moisten two unused swabs, allow them to air-dry, and then package them with the evidence. Examining these control swabs will confirm that any traces found on the victim did not come from the cotton swabs or the alcohol.

At the lab, forensic experts first examine the victim's swabs. If these swabs are negative for seminal fluids but show traces of condom evidence, examiners would then look for the same traces on the suspect's swabs.

Examination of Suspects

If investigators identify and arrest a suspect only a few hours after the alleged assault, medical personnel should examine him promptly. If a suspect has not washed his penis, identifiable traces (either from a condom or from the victim) may be present.

Examiners should moisten two swabs with two drops of isopropyl alcohol, then wipe the penis from the base to the tip. As they did when collecting evidence from the victim, examiners should prepare two control swabs.

INTERVIEWS

With the Victim

In addition to providing general information about the crime, victims may be able to supply valuable details about the condom and its wrapper. They may recall the brand itself or other important details, including the condom's color, shape, texture, odor, taste, and lubrication.

After obtaining facts about the condom, investigators should ask victims about their sexual and hygienic habits, which might account for traces not attributable to the crime. A comprehensive interview would include the following questions:

* Has the victim recently engaged in consensual sex?

* If so, was a condom used? A vaginal lubricant? What brands?

* Does the victim use any external or internal vaginal products (anti-itch medications, deodorants, douches, suppositories, etc.)?

* If so, what brands?

These questions assume an adult female victim. Investigators must modify the interview to accommodate male or child sexual assault victims.

With the Suspect(s)

Investigators also should question the suspect about the condom. A cooperative, honest suspect can reveal the brand, tell where he purchased it, and describe how and where he disposed of both the condom and the empty packet. An uncooperative or deceitful suspect may claim he does not know or cannot remember, or he may name a popular brand but will not be able to describe the condom or the packet in detail.

LEGAL CONSIDERATIONS

When investigators know or suspect that a sexual offender used a condom, they must remember to list condoms on the warrant obtained to search the suspect's possessions. The search of a suspect's home may reveal intact condom packets, but if investigators have not listed condoms on the search warrant, they will not be able to seize this valuable evidence.

CONCLUSION

When sexual assailants wear condoms to commit their crimes, they attempt to protect themselves from disease and apprehension at the same time. Although these crimes become more difficult to solve, investigators should not overlook the evidentiary potential of condom traces. By considering the possibility of condom use while processing the crime scene, supervising medical examinations, and conducting interviews, investigators can ensure that this valuable evidence receives the attention it deserves.

Endnotes

1 In 80 sexual assault cases submitted to the Forensic Laboratory of the Las Vegas Metropolitan Police Department between 9/10/93 and 12/3/93, 19 victims reported that the assailant or one of several assailants had worn a condom during the assault or that a consensual sexual partner had used a condom within 72 hours preceding the incident. Eight additional victims believed that their assailant might have used a condom. Terry L. Cook, criminalist, Forensic Laboratory, Las Vegas Metropolitan Police Department, telephone conversation with the author, December 6, 1993.

2 R.D. Blackledge and L.R. Cabiness, "Examination for Petroleum Based Lubricants in Evidence from Rapes and Sodomies," Journal of Forensic Sciences, 28, 1983, 451-462.

3 R.D. Blackledge, "Collection and Identification Guidelines for Traces from Latex Condoms in Sexual Assault Cases," Crime Laboratory Digest, 21, 1994, 57-61.