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forensics

FW: “Can’t get rid of the blood?”

 

 

Continuing the series of articles about Evidence Collection Training Classes held at SIRCHIE.

Click here for Part 1 – “Have you been fingerprinted?”

Click here for Part 2 – “Where are the Evidence Collection kits made?”

 

Part 3 – “Can’t get rid of the blood?”

 

The morning of Day #3 of Evidence Collection Training classes at the Sirchie Fingerprint Laboratories in Youngsville, NC was spent on the tour of the company’s manufacturing facility. We watched as fiberglass fingerprint brushes were made from start to finish, saw riot helmets being assembled, heard the printing presses rhythmically slap logos and directions onto stacks of waiting cardboard, saw employees counting and rechecking boxes of supplies and chemicals. We witnessed a smoothly running facility. That’s what it takes to insure that the products the law enforcement community uses to catch and prosecute the criminals work. Every time, without fail.

 

After the tour, Robert Skiff (Training Manager/Technical Training Specialist at Sirchie) told us about a new method of fingerprint enhancement developed in Scotland. A bullet can be placed in the middle of an apparatus that shoots electric current into the cartridge and reveals the moisture from a print. This method was demonstrated on an episode of Rizzoli & Isles. Kudos to the show’s writers for including this fascinating technology!

 

Another interesting piece of equipment is the ElectroStatic Dust Print Lifter. Impressions left at a crime scene in the dust on the floor, or on dusty doors or walls, can now be lifted and preserved. A shot of electricity is applied to foil cellophane and any dust below/behind the lifting mat will stick to it. If there is a palm print or fingerprint, it will show up as a mirror image of the original. Rough floors or brick surfaces where a suspect may have jumped, can now be processed using this lifting method.

 

Our afternoon training segment dealt with blood and other bodily fluids.

 

Bloody crime scenes are horrific, but law enforcement officers have to put their feelings aside in order to process and maintain the chain of evidence. Everything they do is aimed at furthering a case to convict, so the scene needs to be secured in order to keep people or animals from contaminating the evidence. If blood is visible at the scene, photographs are taken before the collection process disturbs anything. The photos assist in showing the overall patterns and placement of the drops and splatters. Investigators can determine the approximate place in the room where the victim was first struck, whether the victim was dragged or bludgeoned or shot, if there were one or several victims involved, the velocity of the strike, whether there are arterial spurts, etc.

 

Examples of blood spatter patterns

 

 

 

In order to accurately demonstrate and then analyze the scope and nature of the spatters, the area covered with visible blood is measured and scaled (paper rulers are applied next to the surface being photographed).

 

Blood spatter tagging and scaling

Then it is tagged with information that will help the investigators figure out the sequence of events during the commission of the crime.

Blood Spatter Trail

Specific characteristics of the droplets – whether there is a tail or shaped like an ellipse or a circle, whether small or large circular drops – all reveal information to the investigators and examiners. TV and movie watchers often hear the phrase ‘blunt force trauma’ as a cause of death. This most likely means that the victim has been struck with a baseball bat or a bottle, or a golf club (my fave fictional instrument of death) with medium velocity, so the droplets will be medium sized. (See the drop several inches in front of Mr. Skiff’s finger)

 

A high velocity hit (from a bullet) will have smaller droplets because the blood is broken into smaller pieces as it leaves the body and is sprayed onto the walls or floors.

 

Weapons that are close to the scene or involved in the crime, may get blood on them. They need to be processed for blood as well as prints.

 

Blocking out area of floor of interest to investigator

 

After the visual scans of the room for the visible blood, and the initial photography has been completed, then the areas of possible bloodstains can be swabbed, the samples bagged and identified (as to placement in the room). Presumptive tests can be conducted at the scene, using the Field Kits that contain chemicals commonly used for this purpose. Presumptive tests can help eliminate stains that are not blood, but the stains cannot positively be identified as blood until taken to the lab for confirmation – a detail that TV crime shows frequently fudge.

 

An added level of security for preserving a sample is to make transfers from the original or take chips of the original, but not test the original. That insures that additional tests can be conducted at a later time on the original or pieces of it.

 

 

Unknown Stain

 

 Three transfers were made from an Unknown Stain and then tested with various chemicals.

 

Latent Bloodstain Reagent Products

 

 

 

Unknown stain luminesces

 

 The third transfer was sprayed with a bloodstain reagent, and then the lights were turned off. The Unknown Stain luminesced, therefore indicating the presence of heme, a portion of hemoglobin.

 

If there is no visible blood in the room, but a crime has been reported as having been committed at that site, it is common practice for investigators to work in teams to process the room. The room is darkened, one investigator sprays the walls with a blood search product, while the other marks (tags) the spots that luminesce. The lights are turned on and then the room is photographed, then processed/tested. The method of spraying and tagging is repeated for floors as well.

 

It’s worthwhile to note that blood cannot be destroyed with paint. No matter how many coats, no matter what color paint is covering the evidence of the deed, the tests will always reveal that blood has been spattered beneath it. It gets into every crack and crevice. And it just can’t be washed away. Remember the ‘trace evidence rule’? A crook always leaves something behind.

 

For all you crime show TV junkies out there (I’m one of them): that red blood you see on the bed or wall or floor (hours after a murder has been committed on the show) is strictly for visceral effect. Human blood turns brown or almost black as it dries.

 

 

 

Sexual Assault Collection Kit Record

 

Unfortunately, reports of sexual assault crimes are on the rise. But, ‘He said, she said,’ cases are difficult to prosecute because there are rarely any witnesses to the crimes. Samples taken from the victims need to be pristine and chain of custody must be clearly established. Clothing and bodily fluids need to be collected from the victim as soon as possible after the crime in order to have a chance of catching and prosecuting the perpetrator. A good practice for evidence collection from victims who arrive at the hospital is to have them disrobe while standing in the middle of a sheet. Then the sheet corners can be pulled together, keeping as much evidence as possible intact. Rape victims may not wish to be touched, but swabbing their bodies for fluids, then bagging and testing whatever is collected, may be the only way to tie a suspect to the rape.

 

 

Seminal Fluid Test

A presumptive test can provide important information to include (or exclude) a possible suspect from consideration. There will be an instant (up to 3 seconds) reaction if the unknown substance at the scene or on the victim’s body contains seminal fluid. If the results take longer than that to appear, it must be reported that a false-positive has been found. This might happen if there is not enough of a sample or if the transfer made from the original sample was not good enough.

 

Rape and homicide evidence is kept for years. Bagged, tagged, stored. Photographed and entered in databases as well. If the suspects aren’t caught right away, then the evidence is still there, waiting in storage, to be matched to other evidence that pops up in later crimes.

 

 

*Photos taken by Patti Phillips at SIRCHIE Education Training Center in Youngsville, NC.

 

 

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KN, p. 192 “Deadly Poisons in the House”

 

Sheila and I have been watching an Australian murder/mystery series that recently included poison as a method of getting rid of one of the characters. An interesting case that hinged on who had access to the poison in question.

 

Mystery writers quite often use poison as a way to dispatch the victims in their books. Famed Agatha Christie used poison in several of her 66 novels, on 30 victims. Christie’s choices were based on what she needed to happen in the plot; did the poison have to be fast-acting or was it important to give the killer time to get away?

 

In “What poisons were in Agatha Christie’s books?” I listed a few of her favorite dastardly tools of death, but one of the critical aspects of choosing the correct one was its availability to the murderer.  🙂

 

Arsenic, belladonna, cyanide, etc. may be handy for a pharmacist or a chemist or a doctor, as in the Australian show, but what about the ordinary gal (poison is traditionally a woman’s choice) who wants to do somebody in? It’s not as if a housewife would normally have access to cyanide. Some medications would make you woozy or extremely nauseous if you overdosed, but over-the-counter meds are rarely going to kill someone unless a bucketful is consumed – unless an allergy is involved. There are some exceptions to that, but most will not do the job without some devious planning and execution.

 

So, what is a revenge-focused lay person to do? Assuming of course, that the fictional person is motivated, would have the guts to actually kill someone, and is not squeamish about the cleanup. Dead bodies are messy and hard to drag around.

 

We all have cleaning supplies readily available in the house or garage, so let’s take a look.

 

Bleach This is a fairly common household item used to remove stains from clothing or to kill surface bacteria. It’s well-known to be powerful as a cleaning agent and once upon a time, I poured too much into the machine when I was helping Sheila with the white wash. The shirts basically disintegrated and the ones that didn’t, smelled of bleach forever after. It would be impossible to get this smell past a victim’s nose, so it couldn’t be used in any subtle way.

 

Ammonia is often used to clean windows and is contained in many popular products in a diluted form. The ammonia smell is distinctive and too strong to be pleasant without perfume additives. Used straight out of the ammonia vat? It would burn the skin off your hands while you pass out from the fumes.

 

Remember, our housewife wants to get away with murder, not die while she’s carrying out the dastardly deed.

 

BUT, when these two cleaners (even diluted in the pleasantly scented store products) are mixed together they produce a lethal chlorine gas. If the products have been poured into non-descript spray bottles, the scenario might be to ‘accidentally’ mix up the labels and get the potential victim to help with cleaning after a messy spill in a closed space while the housewife leaves the room. The trick would be to switch the labels back before the cops arrive. Variations of this smelly method might involve cleaning a toilet with one of the clear liquids already in the toilet. After adding the other liquid, the noxious gas would suddenly waft upward toward the victim’s face.

 

Hydrogen peroxide is used as an anti-bacterial agent and some people even use it when gargling or for cleaning small cuts or abrasions.

 

White vinegar is used in cooking and in many restaurants as a gentle, yet effective, solution for shining the stainless steel.

 

BUT, when hydrogen peroxide and vinegar are mixed together, they create an acid, which can be quite harmful to the lungs. Harmful, but not necessarily deadly in small quantities.

 

Dishwasher detergents contain chlorine in highly concentrated amounts, but it’s hard to imagine how you could get an adult to ingest detergent willingly. Perhaps mixed in food? I wonder if it would foam while cooking…

 

Air Fresheners – Most air fresheners include formaldehyde which interferes with your ability to smell and phenol which can cause convulsions, coma, and even death in high enough concentrations and quantities. However, this amount would also kill our housewife while she worked with it.

 

Oven Cleaner contains lye (sodium hydroxide). A little bit of lye is used in old-fashioned soap compounds; too much of the stuff can dissolve skin off the bone.

 

Our housewife might just be better off to find out what food her victim is allergic to, then mix that with a tasty treat to be served at the next get-together. The invitation could read:
“Tea at 4pm. Body Doggie bags will be provided.”

 

The next time you look at the warning labels on the cleaning products, keep these real-life guidelines in mind:

DANGER: can be fatal if swallowed. Less than a teaspoon could kill a 150-pound adult.

WARNING: is harmful if swallowed, and drinking less than an ounce could kill an average sized adult.

CAUTION: is harmful if swallowed, and it would take anywhere from an ounce to a pint to kill an average adult.

 

http://www.achooallergy.com/blog/dangerous-household-chemicals/

 

 

*Please note: this article is posted for entertainment purposes only.

 

 

 

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KN, p. 76 “Save the duct tape and glue the dashboard!”

 

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.

 

Separating folded duct tape 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.

 

Adhesive-side developer

 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.

 

Duct tape prints

 

 

Dashboard prints:

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.

 

Dashboard surface

 

 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!

Dashboard Lift

 

 

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.

 

 

 

 

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