During the medical forensic exam, the medical practitioner will collect a DNA sample from the victim, either cells from the mouth or blood in a blood tube that will be used as a reference standard to identify the victim following a DNA analysis. They may also collect body surface, anal, genital, penile and vaginal swabs, and debris or foreign material that may be found on the victim’s body. These forensic samples are collected based on the scenario of the assault.
Urine samples and/or blood tubes are also collected if the use of alcohol or illegal substances are reported or suspected. The medical practitioner then places all swabs, including clothing worn by the victim in individual bags, and documents and photographs all findings such as cuts, abrasions and lacerations.
DNA Analysis
DNA analysis is an analytical process that allows for the testing of forensic evidence, SCEKs, and other crime scene items to develop DNA profiles that can inform a criminal investigation. If a DNA profile is developed, it is compared to DNA profiles from submitted reference standards, such as victims, suspects, or consensual sex partners to determine whether they are a possible contributor of the DNA profile.
There are 4 steps to DNA testing:
1. Extraction (Normal and Differential): Extraction removes the DNA from the substrate.
2. Quantitation: The amount of DNA present in any sample is quantified to determine how much DNA is present.
3. Amplification: Copies of the DNA are made to provide a sufficient amount of DNA for instrumental analysis.
4. Typing: Genetic analyzers will be used to complete the DNA testing.
Combined DNA Index System (CODIS)
Eligible DNA profiles are then entered into the Combined DNA Index System (CODIS) that is supplied by the Federal Bureau of Investigation (FBI) to support the criminal justice DNA database used at a national, state, and local level to store and search DNA profiles contributed by crime laboratories. CODIS can link DNA evidence obtained from crime scenes, and compare crime scene evidence to database profiles, thereby identifying serial criminals or possible sexual perpetrators.
For a DNA profile to be eligible for CODIS, it must meet three major requirements:
1. There must be documentation that a crime was committed.
2. The DNA sample was recovered directly from the SCEK or other crime scene evidence.
3. The non-victim DNA profile is attributable to the alleged perpetrator. And if applicable, an elimination sample will be requested from a consensual partner.
Elimination samples are needed in sexual assault cases when victims indicate they have engaged in consensual sexual relations within close proximity to the sexual assault. The elimination sample will not have an impact on the collection of the SCEK from the victim, nor the testing process to develop the DNA profile from the sexual assault evidence.
If a CODIS hit should occur with the entered DNA profile, it is considered an investigative lead that requires additional testing by qualified forensic scientists and confirmation from law enforcement.
Following, if a reference sample is needed from the suspect that is identified through the CODIS hit, law enforcement will locate and interview the suspect, as well as obtain a court order to identify the physical characteristics of the suspect, and/or a search warrant to collect a DNA sample.
CODIS is an integral system that is used for data analysis of forensic evidence. Not only does it provide leads to sexual perpetrators, but also links cases within a state and across the nation. It is also beneficial in excluding potential suspects, reducing wrongful arrests, and assisting in the exoneration of wrongfully convicted people.
Victim Privacy and Confidentiality
To protect the privacy and confidentiality of the victim, data entry and sensitive information are limited to those who are directly involved in the case and working directly with the victim pursuant to A.R.S. §§13-4430 and 8-409 (privileged info), and 13-4434 and 8-413 (victim privacy).