Criminals who tie their victims up during the commission of a crime frequently use duct tape for the job. That duct tape is almost always full of prints that get embedded into the tape. It’s practically impossible to manipulate and tear the tape while wearing gloves (I tried this once and the gloves got so stuck to the tape that I threw the resulting mess away), so the crook leaves prints while unrolling and tearing the tape. Even if he has wiped the smooth surface of the tape clean to cover his identity, the sticky side can’t be wiped without taking away the sticky. Balls of tape tossed aside by a suspect have been processed successfully for prints, but first the tape had to be released from itself.
What to do? Drop lots of a 2% chloroform tape release agent on the area where the two pieces of tape meet. Two people need to work together on this – one person places the drops continuously while the other person pulls the tape apart. The ends of the tape should then be folded over (about ¼”) and the tape flattened for 24 hours before doing anything else to it.
After 24 hours, adhesive-side developer should be applied to the sticky side of the duct tape, allowed to sit for a few minutes, then rinsed off. The prints are clearly visible, can be photographed, covered with clear tape to protect them, viewed under an Optical Comparator, entered into the system, and sent off to AFIS.
Up until recently, we could not collect decent prints from the dashboard of a getaway car in a reasonable length of time. Most car and truck dashboards have a slightly bumpy surface, more or less because it’s a selling point to non-criminal types – supposedly the pebbled surfaces mean no more pesky fingerprints to clean off if you’re a mom transporting kids after school. Sheila says the juice spills just get buried in the grooves.
But, it’s a potential fingerprint heaven for the CSIs who need to process the abandoned bank heist car. Think about it. If you press your hand onto a dashboard, your skin (with all the loops and whorls and arches and oils) is also pressing into the crevices of the pebbled surface. The problem is that a straight gel lift or hinge lifter will not pick up the prints effectively or may only pick up the top of the print.
But, the investigator sees the possible print and doesn’t want to lose the opportunity to catch the crook. The answer in the past was to dust the likely area with magnetic fingerprint powder, then apply a Blue Glue gel and wait for the gel to cure before lifting it off the dash – about five hours. FIVE hours? The crook is getting away! No time to wait!
These days, the preferred lifting product (after applying the magnetic powder to enhance the print) is a transparent liquid silicone (PVS200 – polyvinyl siloxane), applied with an extruder gun. It flows down into the crevices, dries in six minutes, and gets into every bit of the print. After the polyvinyl dries, it can be lifted, and then placed on a backing card to preserve the print. At that point, it can be placed under an Optical Comparator, photographed, and sent off to AFIS for an ID/comparison.
This epoxy is not good for every surface (it rips paper, etc) but is very good for pitted, bumpy surfaces like alligator skin and dashboards. Gotcha!
Planning to become a crime scene investigator? Then remember to collect the balls of duct tape tossed on the floor or in the garbage cans at the crime scene. Almost definitely, a great source for prints. And don’t forget your extruder gun!
*Photos taken by Patti Phillips at the Sirchie Education and Training facility in Youngsville, NC.
For more information about Sirchie and its products for the law enforcement community, please visit www.Sirchie.com.
Last week’s article about what Crime Scene Techs really do can be read here.
Warning: parts of this article are extremely descriptive about the work of a CSI at a murder scene.
A Crime Scene Investigator (also known as an Evidence Recovery Technician) is a forensic specialist. A well-trained, experienced CSI tech has an organized plan of action when processing a crime scene. Most go through extensive training, if not in the classroom, then in the field while working with seasoned law enforcement officers, before being allowed to work solo. They study how to recognize evidence, how to document the process and the proper way to prioritize, recover, handle, and package that evidence at the crime scene.
Some of the TV shows and movies touch on the challenges in the job of a CSI, but generally the scriptwriters try not to gross out the viewing audience.
Occasionally, the collection of the evidence requires a strong stomach. If the CSI works a homicide or accidental death scene, they will likely be dealing with strong odors. Although air/water temperature may affect the rate of decomposition, a dead body begins to stink fairly quickly. Think rotting meat. CSIs have various ways of dealing with the odors. Some apply Vicks under their noses, some use medical masks, but some just get used to it.
In case you were wondering: A former CSI told me that the Tyvek suits we see at crime scenes during British TV shows, work very well to keep unwanted fibers and DNA samples away from the scene, but do not block the odors at all.
Sometimes, bodies are dumped in the water, and that affects the rate of decay. The condition of the body recovered from water is a surprise to most law enforcement officers the first time they see it. Unless recovered within the first day or so, the skin and muscle begin to change at such a rate as to become almost unrecognizable for what they are. Special bags are needed to contain the remains while bodies are removed from lakes or ponds. The bags have holes in the sides to allow the water to escape, without losing the body parts.
The condition of a body recovered in the heat can be a challenge on several levels. The body swells up and can pop if not handled correctly. In ‘cold cases,’ where the body has been sitting outside for months, perhaps only the skeleton will remain, requiring identification through dental records or bits of clothing still attached to the bones.
Homicide and some accident scenes can be bloody. It’s fair to say that most law enforcement personnel are deeply affected by the surprising amount of blood found at a murder scene or a particularly horrific accident scene. It’s tough to get used to that part of the job, however much experience you’ve had. But, it’s important to stay detached while collecting the evidence, taking the blood spatter photographs, and detailing the information, so that the victims can be represented properly in court.
On rare occasion, gloves and protective clothing that a CSI wears can rip or tear, exposing the CSI to possible infection or disease.
Stress and even grief can be factors that might affect the CSIs or ERTs. Working on fraudulent documents or stolen property is worlds away from dealing with dead bodies. Some larger departments offer (and even require) grief/stress counseling after emotionally tough cases, but the smaller departments just don’t have the resources for that. Imagine waking up night after night, reliving a crime scene in nightmares. In cases involving multiple deaths or children, the stress level can be especially high.
So, with all the possible negatives/challenges in the job of a CSI, why would anybody do it?
Because of the result. A job well done helps to put the bad guys away.
The job of a CSI changes based on geographic location and the needs of the department. Some towns have no budget for a full-time CSI and hand off cases requiring special evidence collection to County or State personnel. In general, big cities have more homicides and other crimes, so require full-time CSIs. In small towns, the Police Chief or Police Officer might do the investigating, collection and analysis of the evidence.
With those factors in mind, training requirements vary from region to region and from decade to decade. Some departments require college degrees (i.e. Criminal Justice or Forensics) for their law enforcement personnel, with the understanding that specialized training (i.e. photography, computers, etc) might be required as cases come up.
Then after getting hired, the CSI tech will spend some time as an apprentice to a more experienced person – think the ‘probies’ on NCIS, the TV show.
One realistic test to see if possible candidates are really suited to the job of CSI at a murder or accident scene is to have them visit a morgue or an ER. If they get through a busy, bloody night at an ER, they might be able to work in Homicide.
If not, I’m told that there is lots of work in Forensic Accounting and CyberCrimes for CSIs, that does not involve blood or body parts.
*Photos by Patti Phillips
TV makes the job of a CSI tech look like a lot of fun.
It looks like an easy job, too. Get a call from dispatch, arrive at a crime scene, pop on the gloves, shine a flashlight around, take a few photos, collect the evidence along with your team of 4-5 colleagues and go back to the lab an hour or so later, ready to process all of it.
Have the real CSI techs and law enforcement professionals stopped laughing yet? 😉
Here’s the reality:
Most small towns (under 50,000 people) have no CSI lab. None. The local police in smaller towns are able to collect fingerprints, but most have to send them off to a State Lab to be processed.
Many towns, even with a population of 100,000 people, don’t have a ballistics lab to check the caliber of any bullets/casings left behind at the scene or found in the victim’s body.
North Carolina (as of 2019) had a population of 10.48 million, and has three State crime labs – one full service and two regional labs.
New York State (as of 2019) had a population of 19.45 million, and has four State crime labs – one full service and three specializing in varied areas.
New Jersey (as of 2019) had a population of 8.88 million. It has five State labs.
Texas (as of 2019) had a population of 28.99 million, with a full service forensic lab in Austin and 14 regional labs, some conducting only drug testing, and others close to full service.
And all of those crime labs are processing evidence from all kinds of crimes (burglary, robbery, rape, arson, cold case, assault, etc.) not just murders. It take a few hours to get the prints, preserve the evidence, bag and tag it for transport, but it takes months to get it processed, because there is a long line of cases ahead of yours. In some States, the wait is as long as 18 months. That is not a typo, folks. Eighteen months to wait until the evidence can be processed. Even if the case is a high profile one, moving to the head of the line might only shorten the wait to 2-3 months, because there are other high profile cases in line as well or cases that are already in court, waiting for clarification of the evidence.
There is no such thing as instantaneous fingerprint matches. See the article about fingerprint analysis here. There are now handheld machines that scan a viable fingerprint at the scene, but that only speeds up the collection process, not the identification of the fingerprint. (I was recently told that a new fingerprint reader can return an answer in 45 seconds, but some fingerprint experts are reserving judgment as to the accuracy of the matches.)
Get the picture? The State Bureaus of Investigation are short-staffed and the cases more numerous, as attorneys seek to prove or disprove beyond the shadow of a doubt that the evidence gathered at the scene linked their clients to the crime.
In general, the analysts examine all types of evidence related to criminal investigations and assist the criminal justice system. They can provide:
ALL of that evidence must be collected in a thorough and efficient manner by the Crime Scene Technician or Crime Scene Investigator. Cases are won and lost on how the evidence is handled – both the chain of custody and the collecting of the correct evidence can be factors in how a suspect is perceived.
I had a chance to chat with a CSI who has been in the field for about 10 years. She generously shared information about her day – soooo different from the image of the CSI jobs projected on TV.
She enters a crime scene after a Patrol Officer has cleared the house (made sure that no unauthorized person is in it). A Deputy might walk her through the house, and depending on the crime, the owner of the house then walks her through, pointing out items that might have been disturbed or areas where items are missing. She takes notes during the tours so that she can come up with a Plan of Action – how to process the scene.
In general, she will take photos first, and then collect the evidence. If a homicide is suspected, she might take video as well as still photographs.
She might see patterns of wreckage, or concentration of destruction, or even similarities with other cases, but it is not her job to focus on the M.O. (modus operandi) or narrow her collection efforts based on a hunch. She is there to collect all the evidence.
She might be looking for:
What a CSI leaves at the scene is sometimes as important as what he/she collects, so it is vital to be thorough. The detectives and attorneys decide what is significant to the case.
The trunk of a CSIs car is filled with the tools of the trade. They have kits for each type of evidence collection and if they know in general what the scene will call for, they may grab an additional kit from headquarters. They might even carry a tarp to cover the ground (creating a collection place for the evidence) if the scene is outdoors – such as a train wreck.
The CSI I interviewed works in Major Crimes for the Sheriff’s Department, and when she is called to a scene, she works 12-hour shifts, by herself. In most cases, she collects all the evidence, bags and tags it appropriately, and hands it all to the detective in charge. She works 14 days a month, equally divided between the day shift and the night shift. On occasion, a 12-hour shift is not long enough to collect everything at a particular crime scene, so she stays a bit longer to finish. If it looks as if she has to work for another shift, a Patrol Officer will guard the scene until she returns to finish collection on her next shift. If the case merits 24-hour collection (because of weather or the condition of the scene/body) the CSI on the next shift will continue the collection, with any evidence collected up to that point handed over to the new person.
Clear chain of possession of the evidence dictates that in a case where collection goes on for more than one shift, limited people will have keys to the building. There are evidence cards showing who collected it, and anyone entering or leaving the scene will have to sign in and out with the Patrol Officer on duty.
For information about Footwear Evidence, click here.
Next week: The life of a CSI – rewards and challenges.
*Photos taken by Patti Phillips