Here are the answers to the questions we have received so far.
The likelihood of finding the DNA of a sexual assault perpetrator three days after an assault varies and can depend on a number of circumstances. In Massachusetts, survivors can have evidence collected at a hospital within 5 days (120 hours) of an assault. A medical provider at the hospital will use a sexual assault evidence collection kit (SAECK), often called a “rape kit,” to conduct an exam and collect any evidence. After the exam is completed, the kit will be sent to the Crime Lab. The presence of biological evidence, such as blood, semen or saliva, depends on a number of factors, including whether or not the survivor showered or changed her/his clothing before the exam, the type of assault, and the amount of time since the assault occurred. It is important to know that not all kits yield DNA evidence and that the absence of DNA does not mean that no crime occurred. DNA evidence may not be found if:
Unreported SAECKs are stored for the statute of limitations. You can check on the status of a kit by contacting the Forensic Information Line at 866-463-3799.
What are the areas that make up the crime lab?
The crime lab is made up of 18 sections and units, all of which focus on different areas to provide forensic services for Massachusetts’ district attorneys and law enforcement officials. The CODIS, DNA, and Toxicology Units are the most relevant crime lab units that handle sexual assault evidence. The CODIS Unit uses the COmbined DNA Index System (CODIS) to compare crime scene DNA evidence to DNA evidence from other cases to possibly identify a suspect. The DNA Unit analyzes evidence, such as blood, semen and saliva, that is found at a crime scene or is associated with a criminal investigation. Samples processed by the DNA Unit may be entered into CODIS. The Toxicology Unit tests blood and urine samples drawn during an investigation (ex. during a sexual assault exam, if the survivor consents) to determine the presence or absence of drugs that could be used to facilitate a sexual assault.
How can evidence be collected from someone whose breasts and vagina were touched while the person was unconscious if there was no penile penetration?
It is still possible for evidence, including the survivor's account of the assault, to be collected using a sexual assault evidence collection kit (SAECK) even if there was no penile penetration during the assault. The doctor or nurse will determine which steps of the SAECK to complete (such as vaginal swabs) based on the survivor's story. When determining what steps to complete, the nurse or doctor will also take into account that the survivor was unconscious during the assault and may not recall the entire assault.
Can evidence be found on the survivor's underwear following a vaginal rape if the perpetrator didn't ejaculate?
It is possible for there to be evidence from a vaginal rape on a survivor's underwear even if there was no ejaculation. Other types of evidence that may be present on the underwear include evidence from the crime scene (for example, carpet fibers, if any), or any other evidence the perpetrator may have left behind, such as pubic hair.
What common characteristics do perpetrators share, and why do they continue perpetrating?
We know that there are some characteristics that many perpetrators share. For example, most perpetrators target people they know; 75 percent of all survivors know their perpetrators, and 80 percent of all rapes occur in the home. Furthermore, most perpetrators are male; 99 percent of female and 85 percent of male survivors were raped by a male. It is important to note, however, that although most perpetrators are male, most males are not perpetrators. Instead of using weapons, threats, or extreme physical force or violence, most “undetected rapists” (those who have not been convicted or served time in jail) are repeat offenders who premeditate their attacks, identify and isolate victims, and deliberately use only as much force as necessary (such as psychological weapons and alcohol). While there may be many individual reasons that lead offenders to continue to perpetrate, sexual assault is a crime that is often motivated by a desire for power and control.
Can a sexual assault case be prosecuted even if DNA evidence is not found?
While only the District Attorney’s office can definitively say whether or not the perpetrator will be prosecuted, once an assault is reported to the police, DNA is just one piece of evidence in a larger investigation. When determining whether or not to prosecute a case, the District Attorney’s office will also consider the survivor’s account of the assault along with any other evidence that may corroborate this account (for example, physical materials that link the two parties at the crime scene, such as carpet fibers or grass stains, or a Toxicology Kit, if one was completed). It is important to note that not all kits yield DNA evidence, and the absence of DNA does not mean that no crime occurred.
Why is DNA so important, why is it analyzed and what does it prove?
DNA is the unique genetic code that determines many of our individual human characteristics. It is found in most human cells, and, except in the case of identical twins, each person has their own unique DNA code. After the crime lab identifies and analyzes a DNA profile from a suspect, law enforcement can use this evidence to prove that a suspect was at the scene of the crime or had contact with the survivor. If there are no suspects in the case, scientists at the crime lab can search the DNA profile in the CODIS database for a possible match to other crime scene evidence. It is important to note that not all kits yield DNA evidence, but the presence or absence of DNA does not solely prove that a crime did or did not occur.
Can evidence collected in a sexual assault evidence collection kit help to identify the DNA of many individuals that participated in a rape?
DNA is the unique genetic code that determines many of our individual human characteristics. It is found in most human cells, and, except in the case of identical twins, each person has their own unique DNA code. As part of the evidence collection process, the medical provider must ask the survivor if he or she had consensual (willing) sex with anyone in the past 5 days who may also have left behind DNA. This step helps law enforcement determine which DNA was left by a consensual partner and which DNA belongs to a perpetrator. After the crime lab identifies and analyzes DNA profiles from a kit, law enforcement can use this evidence to prove that a suspect was at the scene of the crime or had contact with the survivor. If there are no suspects in the case, scientists at the crime lab can search the DNA profile in the CODIS database for a possible match to other crime scene evidence. It is important to note that not all kits yield DNA evidence, but the presence or absence of DNA does not solely prove that a crime did or did not occur.
This project was supported by Grant #2009-WF-AX-0014 awarded by the Violence Against Women Grants Office, Office of Justice Programs, U.S. Department of Justice to the Massachusetts Executive Office of Public Safety & Security Office of Grants & Research and subgranted to the Boston Area Rape Crisis Center. Points of view in this document are those of the author(s) and do not necessarily represent the official position or policies of the U.S. Department of Justice or the Massachusetts Executive Office of Public Safety Programs Division.