Policy Text
1 (08/28/2017 ) ST. PETERSBURG POLICE DEPARTMENT
GENERAL ORDER
Subject: DNA EVIDENCE
Index as: Deoxyribonucleic Acid (DNA) DNA Evidence
DNA Evidence Procedures, DNA
Accreditation Standards: 83.2.7
Cross Reference: G.O. III -14, Property and Evidence
I.O. V.5:22, Infectious Diseases
Exposure Control Plan
National Institute of Justice, National Commission on the Future of DNA Evidence
FDLE (Florida Department of Law Enforcement) Evidence Submission Manual
Replaces : I.O. V.3:5, DNA Evidence (September 18, 2007)
This Order establishes precautions and guidelines for first responders pertaining to the recognition and safe handling of
potential biological/ DNA Evidence. It also outlines procedures for the collection, storage, transportation and submission to
an accredited laboratory of probable DNA evidence and, lastly, discusses training requirements for employees who collect,
transport and submit such evidence . It consists of the following sections:
I. Definitions
II. Recognition, Responsibilities and Precautions
III. Collection, Storage and Transportation
IV. Training Requirements
V. Submission to Accredited Laboratories
I. DEFINITIONS
A. DNA (Deoxyribonucleic Acid) – The fundamental building block for an individual's entire genetic makeup. It is a
component of virtually every cell in the human body and is the same in every cell. For example, the DNA in a person’s blood
is the same as the DNA in their skin cells, semen and saliva.
1. DNA is a powerful resource in a criminal investigation as each person's DNA is different from every other
person’s, except for identical twins. DNA collected from a crime scene can either link or eliminate a suspect to the evidence
or crime s cene. Through DNA comparison with relatives, a victim can be positively identified, even when no body can be
found. DNA evidence from one crime scene can be compared with evidence from another locally, statewide or across the
nation and can tie the inciden t(s) to the same perpetrator.
2. Valuable forensic evidence in the form of viable DNA can be found on evidence that is decades old. However,
environmental factors can affect the DNA left at a crime scene; e.g., heat, sunlight, moisture, bacteria, and mold, e tc.
Therefore, not all DNA evidence will result in a usable DNA profile. Furthermore, just like fingerprints, DNA testing cannot
tell when the suspect was at the crime scene or for how long.
DATE OF
ISSUE EFFECTIVE DATE NUMBER
August 2017 Immediately V.3:05
Distribution: All Employees
Instructional Order V.3: 05
2 (08/28/2017 ) II. RECOGNITION, RESPONSIBILITIES AND PRECAUTIONS
A. First responders to crime scenes should be aware that DNA is present at almost every scene. Since only a few
cells can be sufficient to obtain useful DNA evidence, it may provide sufficient information to help solve a case.
1. The first responder is primarily resp onsible for the evidence found at the scene. It is their responsibility to identify
what may or may not be useful and ensure that collection and preservation of the evidence is carried out.
2. Recognition of potential sources for recovery of DNA evidence is very important to further the investigation. The
following list identifies common items found at crime scenes which may be good sources of DNA evidence.
a. Guns, knives or other weapons may have DNA on either the handles, butts or other points. Sweat, skin,
blood or human tissue may be present which can be collected or swabbed.
b. Hats, bandannas or masks may contain sweat, hair or dandruff which can be collected and examined for
possible DNA.
c. Eyeglasses, specifically the nos e and ear pieces, are good sources of sweat and skin.
d. Facial tissues and cotton swabs may contain mucus, blood, sweat, semen or even ear wax which may
contain DNA.
e. Dirty laundry may have blood, sweat or semen in or on it.
f. Items which may contain saliva suc h as cigarettes, toothpicks, gum or envelopes.
g. Tape or a ligature (ropes/strings) may contain skin or sweat.
h. Bottles, cans or drinking containers may contain saliva or sweat.
i. Used Condoms may contain semen, vaginal or rectal cells.
j. Bedding (pillow cases/sh eets) may contain sweat, hair, semen, urine or saliva.
k. Bullets that have passed through a person's body may contain blood and/or tissue.
l. Bite marks may contain saliva.
m. Fingernails may be a source of blood, sweat or tissue.
B. If possible , in cases involving DNA evidence, Forensic Technicians should be called to the scene to do the
collecting .
C. Precautions
1. When collecting DNA, the employee gathering the evidence must protect the integrity of the item as well as
themselves against the possibility of an infectious disease.
2. The following precautions should be followed:
a. Wear protective gloves. Change them often.
b. Use disposable instruments or clean them thoroughly before and after handling each sample.
c. Avoid touching the area w here you believe DNA may exist.
d. Avoid talking, sneezing and coughing over evidence.
e. Avoid touching your face, nose, and mouth when collecting and packaging evidence.
f. Air dry evidence thoroughly before packaging.
g. Put evidence into paper bags or envelopes, not into plastic bags. Do not use staples; use evidence sealing
tape.
III. COLLECTION, STORAGE AND