Nationwide, hundreds of thousands of untested sexual assault kits (SAKs)—also known as rape kits—have languished for decades in evidence storage facilities.¹ SAKs are sets of items (e.g., fingernail scrapings, vaginal swabs) collected by medical professionals to preserve evidence from a victim of sexual assault. Investigators then can use this evidence for investigation and prosecution. Many of these kits contain a definitive (and in some cases, the only) piece of evidence linking an offender to a victim—DNA.

Sexual Assault Investigations

Lessons Learned

Beyond just the testing of kits, the findings coming out of SAKI already challenge many assumptions about sexual assault and the offenders who commit it. The authors of this article comprise a unique group of experts—academic researchers, a forensic specialist heading up BJA’s SAKI, and members of the FBI’s Behavioral Analysis Unit. They have collaborated on this project because they bring distinct perspectives from which to contextualize the SAKI findings. As a result, the following five recommendations are suggested for law enforcement agencies investigating sexual assault.

Recommendations

1) Consider that a rapist possibly has done this before, will continue to do this in the future, or both.

Much of what people know about sexual offenders, especially serial sex offenders, comes from convictions and self-reports. This leads to an unrepresentative sampling of sexual perpetrators. In research on self-reported proclivity to commit rape, approximately 35 percent of surveyed male college students indicated some likelihood of committing a rape if given the opportunity to do so without facing consequences.⁴

It is important to note three things about this statistic. First, it comprises individuals willing to report this proclivity on a survey and most likely undercounts the true number. Second, a significant number of respondents may not actually be willing to offend because they lack the opportunity to do so with impunity. Third, it is possible, and perhaps even likely, that at least some of these individuals did commit rape and either were caught later in life or continued as unknown offenders. Thus, there exist plenty of potentially motivated offenders.

Concerning convicted offenders, prior recidivism research on sexual offenders shows that approximately 5 percent of individuals released from prison for a sexually based offense were rearrested for another such offense within 3 years.⁵ This is a relatively low rate of recidivism, but, again, these estimates are based on knowledge of repeat offending from official criminal justice records. Additionally, limiting the notion of recidivism to a 3-year window ignores the potential for offenders to revert to offending once initial post-release scrutiny (e.g., probation, parole, mandatory sex offender treatment) ends.

In contrast, DNA evidence collected from these now-tested kits can connect previously unlinked sexual assaults through more objective means and without the prism of self-reporting. Also, this data hinges on evidence gathered at the time the kit was collected, not at conviction, which provides a more representative picture of reported sexual assaults.

Research found that serial sex offending proves much more common than expected—approximately a third to a quarter of subjects identified as part of these SAK initiatives were serial offenders.⁶ These are low estimates and only represent those cases reported to law enforcement to begin with and where DNA was collected and eventually tested.

Practically, this means several things had to happen:

• The victim reported the sexual assault
• A kit was collected
• The kit included enough DNA from the offender for testing
• Law enforcement retained the kit
• Personnel submitted the kit for testing
• The kit had enough DNA information to meet DNA database eligibility

A breakdown at any of these steps means the DNA did not make it into the system, and the rapes would not be linked.

Data coming from these jurisdictions also shows what happens when criminals can continue to offend. One such offender is Nathan Ford. DNA has connected Ford, a former probation officer, to 18 rape kits in northeast Ohio to date and to several other sexual offenses for which there exists no DNA—rapes that span decades.⁷ These only are the offenses involving Ford that law enforcement knows of. No one could have realized the full extent of his offending had it not been for the now-tested SAKs.

2) Do not assume a consistent modus operandi and victim preference.

While it may be likely that an offender has committed other sexually based offenses, investigators cannot assume the perpetrator kept the same modus operandi (MO) or victim preference across incidents. Standard investigative practice in many law enforcement agencies involves either investigating a sexual assault allegation as an isolated event or using the offender’s MO or victim preference to link other sexual assaults to the offender. However, research calls this practice into question and shows that offenders often vary their MO drastically across assaults.⁸

Nathan Ford seemingly chose many of his victims at random, with varying MOs and victim preference.⁹ This made it exceptionally difficult to link his cases together. His victims included high-risk women with substance abuse issues and histories of prostitution, a college student, a schoolteacher, and three teenagers, among others. He dragged some of his victims from the street into secluded areas, assaulted one during a home invasion, and attacked another while she studied on campus.

Serial sex offenders frequently assault both strangers and acquaintances and often exhibit intraserial variations in victim relationship, age, and even gender. For example, one offender identified as part of Cuyahoga County’s SAKI was connected to two sexual assaults. First, he was one of four offenders who sexually assaulted a female juvenile stranger at a party. His second sexual assault occurred 2 months later, and the victim was his 3-year-old son.

Just because an offender and victim have a domestic relationship or know each other does not mean the offender does not also have victims who are strangers. In fact, investigators should expect to find victims who are strangers.¹⁰ The best way to link offenses is by collecting and testing SAKs, even in domestic sexual assaults where the offender is a named suspect or has confessed.

Next, officers must prepare to explain to prosecutors, judges, jurors, parole boards, and other related parties that offenders do not necessarily follow substantially similar patterns across offenses. For example, one offender identified as part of the Kansas Bureau of Investigation’s SAKI began committing forcible rapes at the age of 15. His victims often were underage female acquaintances from unstable homes. In less than 3 years, four different victims reported that he had raped them. The victims in the first three incidents were acquaintances of the suspect. The fourth was an intimate partner. A few weeks after raping the fourth victim, he kidnapped and beat her. He strangled the woman to a state of unconsciousness, buried her in a shallow grave for a short time, and then held her captive in his basement for days before allowing her to leave.

3) Do not rely solely on DNA to solve a case.

While SAKs can prove extremely useful to law enforcement for all the reasons detailed, officers cannot assume that DNA is the only investigative tool necessary. Not every kit will contain CODIS-eligible DNA, and not every CODIS-eligible DNA profile will identify a known offender or provide an investigative lead. While advanced methodologies, such as forensic genealogy, certainly can help identify numerous suspects, estimates suggest that DNA will not be the key to solving over 50 percent of cases.¹¹

Behavior cues present at the scene also can help link offenders. The FBI’s Violent Criminal Apprehension Program (ViCAP) proves ideal for helping to connect cases. As such, in early 2017, the BJA’s SAKI team partnered with ViCAP to increase use of the database and sharing of information from SAKI-related cases across jurisdictions and the country.

This may seem to contradict the previous recommendations. In fact, these recommendations complement each other. ViCAP, in addition to DNA testing (where applicable), allows law enforcement to use crime scene evidence more exhaustively. It also proves crucial to remember that most sexual assault cases produce a surviving witness who often can provide key information regarding the suspect, such as physical appearance, speech pattern or accent, MO, and type of vehicle. Investigators can link all these potential identifying features across jurisdictions and states by sharing data in ViCAP.¹²

4) Do not assume sexual offenders only commit sexual offenses.

Research on the criminal histories of sexual offenders identified via previously untested kits in both Cuyahoga County and Wayne County found that most offenders did not have a prior arrest or conviction for rape in their criminal history. However, almost all of them had at least one arrest for a different serious offense, with violent offenses frequently appearing in their criminal histories.¹³

Some of these other offenses may have been precursors of, or related to, sexual assaults; however, many of them simply may show that these offenders are criminally versatile. This means that focusing investigative efforts on sexual offenders potentially can reduce not only sex offenses but also other crimes.

For example, one offender identified in Cuyahoga County was linked to two now-tested kits, one from when he was 13 and the other 15. In the decades that followed, he never was arrested for another rape, but he was arrested and convicted for several other crimes, including felony assault, motor vehicle theft, theft, robbery, kidnapping, and aggravated murder.

5) Be patient, understand the limitations of CODIS, and verify that DNA from convicted offenders of interest actually is in the database.

The SAKI already has resulted in the addition of over 16,000 profiles to CODIS. Profiles remain in the database, potentially solving future crimes. The more profiles added to CODIS, the more robust the database becomes. An expanded DNA database enables law enforcement to better identify persons convicted of violent and sexual offenses who also are involved in unsolved crimes and who may reoffend after release.

This is why testing kits associated with sexual assaults committed by nonstrangers, from incidents that occurred outside the statute of limitations, and from victims who do not want to prosecute proves so important. DNA profiles extend beyond the crime in question. Law enforcement may be unable to get justice for a particular victim, but they might for past or future victims.

Sexual offenders may, and often do, have prior arrests or convictions. However, investigators cannot assume that these offenders' DNA already is in CODIS. Typically, eligible convicted offenders from whom DNA lawfully can be collected include those arrested, facing charges, or convicted of murder, sexual abuse, kidnapping, or other qualifying state offenses.¹⁴ However, numerous jurisdictions have discovered gaps in the collection of lawfully owed DNA. This refers to a DNA profile from a qualifying offender who should have a sample in CODIS (based on the type and time of the offense in relation to applicable state law) but from whom a sample never has been collected or entered into the database. In some instances, thousands of profiles are missing.¹⁵

It is crucial that agencies test unsubmitted SAKs and upload all eligible profiles to CODIS. However, cases will remain unsolved unless evidence profiles can match against convicted offenders’ profiles. The absence of lawfully owed DNA samples in CODIS likely will result in missed opportunities to identify perpetrators of many crimes, including sexual assaults. For example, Michigan demonstrated the importance of lawfully owed DNA collections in 2011 when its department of corrections collected samples from 5,000 prisoners who had slipped through the cracks. Subsequent DNA hits in CODIS were linked to 74 crimes, including 5 murders, 23 rapes, and 3 armed robberies.¹⁶

Investigators also need to remain aware of local and state laws impacting their ability to upload convicted offender DNA to CODIS. These include state DNA laws, most of which only allow entry of a suspect’s DNA into CODIS for convictions associated with crimes after 1994 or 1995, when the laws were enacted. As such, many offenders (incarcerated, paroled, or deceased) associated with older cases may not have had their DNA entered into CODIS. Investigators should verify specific individuals of interest with their local or state CODIS administrator.

Conclusion

Testing the evidence contained in SAKs is crucial and, in most states, no longer optional for law enforcement. The benefits explained in these five recommendations make it clear that law enforcement must do all it can with the forensic advancements now available to bring justice to the victims of sexually motivated crimes. However, testing is just the first step—it should be followed by investigations and prosecutions. SAKI grants provide as much funding for prosecutions and investigations as they do for testing kits. Ultimately, both testing evidence and sharing information are key to identifying suspects and reaching successful prosecutions. There is little doubt that doing so will help identify offenders and also prevent those who are likely to reoffend.