Whether a big-city patrol officer or a deputy serving a small, rural community, access to forensic services is often limited. Sure, major crimes bring out the crime-scene folks, but most officers see hundreds of burglaries and auto thefts for every rape, murder or similar major case. Officers may be limited in the amount of evidence gathering they can effectively accomplish due to time, resource or training limitations. And in many areas, gathering forensic specimens is something officers just don't routinely do.
Good news: A complex, and yet simple-to-collect evidence sample is within your reach and ability.
Deoxyribonucleic acid (DNA) is often referred to as the building block of life. Contained within every cell of every organism, DNA provides the almost unique pattern for each individual specimen. Indeed, except for twins and cloned organisms, every organism contains its own, unique set of code within DNA. Through a variety of methods, microbiology can transform DNA into a readable, comparable code, permitting its use as an identification method.
Body fluids, such as blood, semen and saliva are the most commonly encountered sources of DNA. Body tissue, including skin, also contains DNA, as does the roots of hair. However, body wastes, such as sweat, urine and fecal matter will not contain DNA on their own.
Since DNA was first used in forensic applications in the mid 1980s, laboratory procedures have rapidly evolved. Previously, an identifiable stain the size of a nickel was needed for a serologist to obtain the desired genetic code. Today, technological advancements allow lab experts to produce more than enough DNA for identification from a barely visible stain. Statistical analysis also has progressed tremendously, to where most analyses produce probabilities of one-in-a-billion or less.
Tools of the Trade
How can this high-tech tool aid a patrol officer? First, it's easy to conduct evidence collection. The necessary tools are inexpensive, even free. And collection is rapid, thus not tying up an officer who has calls waiting.
Jennifer Howell, a crime-scene investigator with the Palm Beach County Sheriff s Office (PBSO) in West Palm Beach, Fla., has extensive experience in DNA recovery. While she uses packaged evidence collection kits, she says you can put together one very easily. The tools would include cotton tipped swabs, surgical gloves, distilled water, alcohol wipes and coin or mailing envelopes.
Between an office and local emergency room, an officer can probably obtain all of these items, if not the entire list. And this short group of products is capable of collecting hundreds of evidence samples, for less than $10.
The materials used to collect DNA should be sterile. However, Howell notes that sterile, in this case, does not mean medically sterile, but rather new and untouched. Bathroom swabs, grocery-store distilled water and office-supply store envelopes will provide the level of cleanliness necessary.
Help for Handling
Howell explained the basic technique for DNA sample collection. First, don a new, fresh pair of gloves. If the sample is liquid, merely swab the material. If dry, first moisten the swab with distilled water without over moistening, which will unnecessarily dilute the DNA. Then swab the stain. Swab the stain with only enough energy to loosen and collect it.
Place the swab into a clean, unused envelope. Close and seal the envelope with tape, mark the exterior as appropriate and submit it as evidence. Upon completion of the collection, use an alcohol wipe to decontaminate the mouth or applicator of the distilled-water container.
Contamination issues are important to consider. Each of us has our own DNA, which may be transferred to the sample if we aren't careful. For this reason, start with clean gloves. Then, avoid coughing or sneezing in the area to be sampled. Because hair contains DNA (especially the roots), you must not add your hair to the scene. Use a hairnet, Tyvek head cover or shower cap to prevent hair from falling onto the evidence. Similarly, be wary of loose pet hair contaminating a sample. And don't lick the envelope to seal it use tape. Howell notes that the crime-scene investigators of the PBSO wear full Tyvek coveralls on major scenes due to the often extensive DNA collection.
How should you approach a situation in which you suspect fingerprint evidence is also present? Howell explains that fingerprint dust does not damage or camouflage DNA. If dusting for prints, process a scene or item for latent prints, and then sample for DNA.
Dan Nippes, the director of the Regional Crime Lab at Indian River Community College in Ft. Pierce, Fla., notes that the way evidence exists is the way you want to sample it. Don t take this to mean that a scene, entered for suspect search and safety, cannot be sampled. You can easily obtain standards from any officers who may have touched surfaces prior to the scene being processed; likewise, people with legitimate access may be sampled for use in elimination, just as officers obtain elimination fingerprints.
With the development of more sensitive methods for analyzing DNA, previously impossible sampling can be conducted. Touch DNA is what's left as a result of perspiration transferred to a door knob or firearm, for example. It's not a given; sweat does not contain DNA, but if it contains live skin cells, DNA can be recovered from them.
You must store and handle a sample with respect. First, always package in paper, such as an envelope, and allow it to air dry. Store it in a cool, dry location. Transport it to the lab as soon as possible, where it will be maintained in climate-control devices. Protect it from moisture, heat and, most importantly, from contamination.
Again, nothing unusual, just good police evidence handling.
Earlier I mentioned obtaining standards. Previously, this required a blood draw, an inconvenience for witnesses and victims, and consent or a court order for suspects. Lynn Park is the chief of the Major Crimes Division of the State Attorney s Office for Florida s 19th Judicial Circuit, serving the four counties of Florida s Treasure Coast. Park has had the opportunity to prosecute hundreds of the most heinous violent crimes on the Treasure Coast, and found DNA to be a valuable tool.
She notes that the manner in which DNA standards are now collected does not require a court order, thus simplifying the collection of standards. Very simply, use a new sterile swab, handled with gloves, to swab the inside of a cheek. The swab collects a combination of saliva and epithelial (skin) cells containing DNA. Place the swab into a new, clean envelope, seal with tape, mark it and submit to the lab. To avoid contamination issues (especially such as those that plagued the O.J. Simpson case), do not transport standards with unknown crime-scene samples.
Sergeant Bill Springer is the supervisor of the Cold Case Unit of the PBSO s Violent Crime Division. He s often referred to as Sgt. Swab by crime-scene personnel because he believes that if investigators don t look where DNA may be, they will not find it. In a recently reworked 1996 homicide case investigated by the PBSO, DNA evidence proved successful. Technology had changed since the initial case, and investigators were able to recover DNA from a ligature, identifying a suspect in the case. In another incident, semen was identified as a suspect s; this person had stated he had not been involved with the victim, and the DNA findings provided a powerful tool for investigators to re-interrogate him.
How much DNA should you collect? Nippes explains that common sense should apply. Look at the crime scene, imagine being the offender, victim or witness, and apply that logic to your search. It s usually not necessary to sample every visible stain unless multiple offenders are suspected or there was an exchange of body fluids one stain will suffice.
The Value of CODIS
A federal agent relates a recent incident during which an AK-47 was recovered from an abandoned house. Test firing of the rifle determined (through the National Integrated Ballistic Information Network) that it had been used in a drive-by shooting. The rifle was swabbed, the DNA found was entered into the FBI s CODIS (Combined DNA Index System), and it identified a suspect in the shooting.
CODIS, an FBI-managed system, links laboratory DNA systems nationwide. CODIS stores two types of information DNA recovered from crimes defined as violent crimes, and offender DNA as required by various states legislation. Nippes explains that CODIS compares the information on 13 loci of the DNA helix and reports whether a match was identified within the millions of case and offender records maintained by it. CODIS has proven valuable for linking crimes, identifying offenders to crimes and even identifying decedents whose DNA has been collected as a CODIS record.
An important aspect of CODIS is the list of violent crimes it stores as cases. Homicide, sexual assaults, aggravated assaults, robberies, and bomb or arson offenses of course constitute violent crimes. However, as in other federal laws and programs, residential burglary also is defined as a violent crime. Thus, one of the most common crimes, with one of the greatest impacts on society, is included in this unsolved-crime database.
Nippes sees several directions for the future of DNA analysis. As both technology and understanding improve, law enforcement forecasts the ability to discern more information from DNA evidence. As it improves, it will provide greater investigative leads, such as the race, sex and other aspects of the donor. Animal DNA, currently only processed by a number of Fish & Wildlife and veterinary labs, and for a limited number of species, will become a more important form of evidence. It will lend itself to greater use in wildlife investigations, and become a more valuable tool to the traditional criminal investigator. Finally, as technology improves, the criminal justice system will be able to better and more quickly utilize DNA evidence.
The Waiting Game
Currently, the biggest problem facing DNA processing is case backlog. Nippes explains a single sample requires approximately 14 hours to process. The average DNA analyst only handles three to five cases per month. For each case, an analyst must maintain equipment and conduct extensive quality assurance activity. Indeed, 25 percent of analytical time is quality control, and 25 percent of all samples are for quality control. Many crime labs are reporting backlogs of up to three years.
Two things will help alleviate backlogs. First, investigators must understand that not all samples require analysis. Springer explains that at the PBSO, major crimes require case meetings involving the detectives and crime lab. At these meetings, evidence is examined and decisions made regarding which evidence will be analyzed and what analyses are necessary. In a case that features 100 or more swabs, the meeting may determine that a very limited number will actually be analyzed, thus preserving precious resources and limiting backlogs.
Nippes agrees with this need for filtering by the investigative team. He also notes that when investigators use presumptive field tests to locate body fluids, they should practice quality control on their materials. Before using a presumptive agent such as phenolphthalein, have a method to test the material first to ensure it will react to blood as expected. Chemicals age and lose potency. If the chemical provides either false positives or false negatives, it wastes everyone s time and efforts replace it with fresh, reactive material.
Nippes also notes that the second and most valuable way to cut backlogs will be to increase the size of serology units in the various crime labs. Already, funding from various federal programs has significantly increased laboratory manpower. However, as the value, acceptance and utilization of DNA analysis increase, so must laboratory staff.
Example: In Louisiana, the serial killer investigations along the I-10 corridor created a tremendous increase in the equipping and staffing at the Louisiana State Police Crime Lab. However, this lab has also seen a steady increase in submissions from agencies in the field, plus a tremendous workload as offender samples are submitted for inclusion in the CODIS program.
These shortcomings require understanding and patience of each officer on the street. Nippes explains that the Indian River regional lab must prioritize cases. Homicides and sex crimes receive the highest priority, while others are worked relative to their rank within the system. Thus, a murder detective may see lab results within a month, whereas a vehicular burglary investigator may be waiting at the three-year point for analysis, or for a trial subpoena as a tickler. The lab wants to produce results in every case, but the speed of the results will vary based upon priority.
The staff at PBSO emphasizes its team approach to cases. Even on minor cases, an officer can follow this protocol: Contact the lab, discuss the specific case, determine what evidence is most crucial and discuss what specific analyses must be conducted. Working together, both those in the field and laboratory can become stronger and produce more relevant findings.
DNA is a tool available to every officer. Collection is simple to conduct. The supplies are inexpensive. Processing time in the field is minimal. Standards are easily obtained. By recognizing contamination issues and the needs and status of the lab, a patrol officer can ensure samples are used to their highest potential. DNA evidence, often thought as being only for a crime-scene specialist, can then be found in every officer s tool box.
Paul R. Laska retired after 29 years in law enforcement on Florida s Treasure Coast as a crime-scene investigator, fingerprint examiner and bomb technician. Contact him at firstname.lastname@example.org or visit his Web site at www.paulrlaskaforensicconsulting.com.