DNA Biology

Examiners in the Forensic Biology specialty routinely examine items of evidence for the presence of blood and seminal fluid. After the proper samples for comparison are obtained, DNA analysis can be conducted on these stains, and conclusions drawn as to whether an individual can be eliminated or included as a possible contributor to the genetic material identified. When the DNA database is completed, the DNA profile obtained from an unidentified assailant will be compared to the profiles in the database of convicted offenders for a possible match.

Analytical Methods

Biology Case Acceptance Policy

This policy is intended to serve as a general guideline for evidence submission to the ISPFS Biology Section. This policy provides clarity and ensures consistent processing of cases across all Idaho law enforcement agencies while maximizing ISPFS resources. Case circumstances vary, and sometimes, deviation from this policy may be necessary. These deviations must be approved by ISPFS staff before testing.

It is essential to familiarize yourself with this entire document before submitting evidence.

See the ISP Evidence page for proper packaging and storage recommendations.

Testing Capabilities

The ISPFS Biology section is capable of examining items of evidence for blood, semen, saliva, urine, feces, wearer DNA, male DNA, and touch DNA (homicides and certain sexual assaults only) and performing both STR and Y-STR DNA analyses. Providing detailed agency reports and specifying the type of testing(s) needed on the service request is essential to processing your evidence appropriately.

Sexual Assaults: Female victim/male suspect sexual assault kits will be tested for the presence of male DNA instead of traditional body fluid identification. Other types of sexual assault kits, including male victim/male suspect, female victim/female suspect, and male victim/female suspect, will be processed directly for DNA. Please include the gender assigned at the victim’s birth, suspect, and other relevant individual(s) on the laboratory service request.

Semen/Saliva: Microscopic identification of spermatozoa or serological testing for specific body fluids is not performed on sexual assault kits. If this testing is required for court purposes, a written/electronic request from the prosecutor must be provided. This request must detail why serological testing is required for trial and what additional probative information it would add to the case. Serological testing is performed on non-kit items such as clothing or bedding; a written request is unnecessary.

Blood: This testing is performed using presumptive tests only. If animal blood is suspected, or confirmatory testing for human blood is required for trial, please include that information on the service request or inform the laboratory during evidence submission.

Touch DNA: This type of testing is generally only offered on homicides and certain types of sexual assaults. More information regarding accepted evidence is provided in the evidence submission section below. Ineligible items may be swabbed for touch DNA by ISPFS for preservation purposes only. An independent laboratory can then test these samples. This service is only offered by request; approval must be obtained before submission.

Wearer DNA: This testing is performed on worn items, such as clothing or jewelry, to identify who the item may belong to. We do not perform this testing if the item’s owner is already known.

Consumption: Items expected to have very low amounts of DNA, such as minute blood stains, touch DNA samples, and hair roots require consuming the entire sample to provide the best possible result. The biology section requires consumption authorization before testing these items, which typically comes from the local prosecutor. This authorization may come directly from the submitting agency; however, it is highly recommended to consult a prosecutor before providing authorization.

*The submitting agency will have 60 days to provide documentation authorizing permission to consume. After 60 days, the evidence may be returned without further analysis. The evidence may be resubmitted once permission to consume has been obtained.

Cross-Discipline Requests: Many nonporous items are suitable for DNA and latent print analysis. When possible, ISPFS will attempt to perform both services when requested. However, some handled items will be best suited by only one type of analysis, as both disciplines would need to process the same area. Please contact the laboratory before submission to discuss the best options for your evidence.

Oversized Items: Large items such as couch cushions, area rugs, and mattresses are difficult to fit inside the laboratory. Please contact the biology section to discuss whether swabs or cuttings of certain pertinent areas could be submitted instead of the whole item. If the entire item must be submitted, please utilize packaging that covers the evidence completely and is sturdy enough to repackage after examination.

Human Remains Identification: For body identification, a known secondary reference from the presumed individual, such as a toothbrush or baby tooth, is best for comparison to the human remains. If no secondary reference exists for the individual, a kinship analysis to direct family members of the presumed individual may be performed. The order of preferred kinship samples is as follows: biological parents, mother, father, biological child, full sibling, half-sibling. Due to the nature of sibling relatedness, sibling comparisons are not always informative. Cousins, grandchildren, etc., are unsuitable for the kinship analysis performed at ISPFS. Contact the biology section to discuss the best samples for comparison in your case, as well as testing options that may be available at other laboratories.

Control Swabs/Substrate Controls: These items are not accepted for testing.

GSR Testing on DNA Items: It is recommended that evidence be tested for GSR before being submitted to the laboratory for DNA testing.

Evidence Submission

Sexual Assaults: The initial submission will be limited to the sexual assault (SA) kit, one condom (if applicable), and relevant references. No additional submissions will be accepted for positive kits unless case circumstances, such as multiple perpetrators, dictate the need for additional analysis. Penile and/or hand swabs from suspects will only be accepted if a known reference from the suspect has also been provided. Foreign matter collections inside kits will not be examined unless swabs are present. Requests to examine these collections may be considered case-by-case if the kit is negative.

If the SA kit is negative, a second submission of clothing or bedding will be accepted, and serological testing for specific body fluids will be performed. Prior approval from the laboratory must be received before this submission. Clothing submissions require a known reference sample from the primary wearer of the item (i.e. suspect reference is required for testing the suspect’s underwear).
Touch DNA testing may be performed on clothing and body swabs in stranger sexual assaults or sexual assaults of children. Please contact the biology section before evidence submission if this testing is needed.

Homicides: If cases involve one suspect and one victim, the first submission is limited to five (5) evidentiary items. It is highly recommended to contact the biology section before submission to discuss the specifics of your case. This will ensure the most relevant evidence is included in the first round of testing.

If more than one crime scene, suspect, or victim is involved, the laboratory will accept up to eight (8) evidentiary items in the first submission.
If probative information is obtained from the first submission, additional items will not be accepted unless special circumstances exist and the laboratory, investigating officer, and/or prosecuting attorney discuss the submission of this additional evidence.
Additional items may be submitted if no probative information is obtained from the first submission. Please contact the laboratory to discuss additional testing. Additional samples will not be tested to merely disprove all possible scenarios.
Touch DNA analysis is permitted on weapons in murder and attempted murder cases.
Testing of blood trails is limited to two samples unless special circumstances warrant additional samples.

Property Crimes: The first submission will be limited to two (2) evidentiary items unless there is reasonable belief multiple perpetrators may be involved.

Criminal Possession: Criminal possession cases of firearms or drugs are not accepted for DNA analysis.

References: Known reference samples from involved individuals are not included in the number of evidence items accepted above. These samples can be blood or oral (buccal) samples.

To expedite the testing process, known reference samples from all involved individuals should be submitted simultaneously as your questioned item(s). This includes references from individuals whose DNA may be present unrelated to the crime, such as property owners, etc.
Except for sexual assault kits, known reference samples must be packaged separately from the evidentiary material.
The packaging of known reference samples must be labeled with the full name of the individual from whom the sample was collected.
Medical Examiners/Coroners typically will not submit known reference samples from criminal investigations directly to the laboratory on your behalf.
An individual’s known blood or oral (buccal) sample is required to determine if their DNA is present on your evidence.
If a suspect has not been generated or a known sample from the suspect cannot be obtained, the questioned items may be tested without known reference samples provided the questioned samples are CODIS eligible.
If a CODIS hit is obtained, a known reference sample from the subject is required to confirm the CODIS hit.
A known blood or oral (buccal) sample from consensual sexual partners (intercourse within 96 hours before a sexual assault) is needed for elimination purposes and should be submitted. If unable to obtain, submit documentation regarding the attempt to do so.
Oral/Buccal swab collection should utilize two swabs from one or both cheeks. Left and right cheeks should not be collected separately. Submissions of separate left and right cheek swabs will result in one sample being rejected at intake.

Rush Testing: Rush status must be approved by the laboratory and can be given to cases for the following reasons:

Exceptional public safety risks such as home invasion, sexual assault, stranger homicide, or sexual assault of a child by a custodial adult.
Safety risk to the survivor or family, such as a specific death or physical violence threat when the suspect is not in custody.
Jury Trial date. The laboratory will only rush for trial, however please inform the lab of any pending court dates for your case. If your trial has a discovery deadline, you must also provide this date. Notice must be given to the biology section at least 60 days before the date the results are needed.
DNA testing for body identification is requested by the Medical Examiner.
Processing of a surreptitious sample or reference sample to facilitate an arrest on a homicide, sexual assault, or serious assault case.
Please inform the laboratory during case submission if you need to request rush testing.