Archive for the ‘Evidence’ Category
There’s more to evidence collection than merely bagging and tagging bloody clothing and spent bullet casings. Crime scene techs are highly trained, skilled members of police agencies and forensic laboratories who more often than not provide the keys to solving cases.
In the “good old days,” many officers collected their own evidence. They plodded into and poked around crime scenes, determining what items they thought might be of some value, and then tossed those things into some sort of containers—grocery bags, envelopes, boxes, and even the cellophane wrappings from cigarette packs. In those days there wasn’t a lot of consideration for sterility, and DNA hadn’t yet made it’s way on the scene.
When investigators finally discovered plastic sandwich and ziplock bags you’d have thought they’d won the lottery, because packaging evidence had suddenly become a breeze. The problem with those new-fangled containers, though, was that detectives were placing everything in them, not knowing they could be destroying or damaging evidence instead of preserving it. And that brings us to the question of Paper or Plastic?
There’s a simple rule of thumb for deciding which type of evidence packaging—wet evidence goes in paper containers (wet evidence can degrade if placed inside plastic containers) and dry evidence goes in plastic. Items that could be cross-contaminated must be packaged separately. There’s a rule of thumb for other types of evidence, too, and here’s a handy list for the proper packaging of those items.
Hair – Double packaging in paper is best. However, if the hair is completely dry, plastic will work in a pinch. Hairs recovered from different locations must be packaged separately and labeled accordingly. Tape all packaging seams.
Fibers – Dry, and tape-lifted, fibers may be placed inside plastic containers.
Rope, twine, and other cordage – Paper or plastic.
Paint chips – Place inside folded paper. Then place the paperfold inside an envelope.
Tools – Paper or cardboard.
Tape – Wear non-powdered gloves when handling tape. Submit samples inside plastic. If the tape is stuck to an item the item must be submitted with the tape still attached. Do not remove the tape!
Glass – Wrap in paper. Smaller pieces may be placed inside appropriate size cartons.
Arson and other fire evidence – Airtight metal containers. Unused paint cans work best.
Dried stains – Wrap stained item in paper or place inside cardboard box. Large items – moisten swab with distilled water, swab the stain, and package in paper or cardboard after drying.
Blood - Allow to air dry and then package in paper.
Evidence drying lockers
Working as a deputy sheriff in a rural county often presents its own set of special and sometimes unusual challenges, especially during the days before the existence of GPS, cellphones, and radio repeaters. In other words, it was pretty darned easy to get lost while traveling a convoluted maze of paved (sort of), dirt, and/or gravel roads. Roads with names like Burnt Tree Road, Red Clay Way, or Turkey Trot Lane.
Many of those winding back-roads led to five or six house communities where it was the norm for us to stop and ask for directions, and some of those kind folks, thinking it would be best for us to speak directly to the person we sought, allowed us use of their telephones. Besides, they didn’t want to be known as the one who sent the law after their friends. After all, liquor stills and pot grows were pretty popular in those days.
So, after a couple of rings and a loud “Hell-Oh,” this is what we sometimes heard as a response to our requests for directions to someone’s home.
“Go past Robert Junior’s old horse barn—the old one, mind you, not the fancy new one—and hang a sharp right at the big oak tree. Then go on down until you see a red mailbox. That ain’t ours, but you’re close. We’re just past where John Henry Daniels used to have a store. Now, it burned down 37-years ago next week, but they’s a big rock there with some yaller paint on it. Yaller was John Henry’s favorite color so his wife, Etta Jean—she’s Romey and Winonna Jenkins’ oldest daughter—painted the rock so’s everybody’d remember him and the store. If’n you knowed him you’d know John Henry sold the best pickles and peaches this side of Atlanta. That he did.
Anyways, if you get to where the road splits into a “Y” you’ve done gone too far, so turn around in Mable Johnson’s driveway—it’s the one with the deer head a-nailed to the cedar post next to road (her daddy used to be a taxxy-dermis)—and head back the way you come. Our house is the blue one a’settin’ off the road about two-hundred yards—the one with the goats and chickens running ’round the place. You can’t miss it, ’cause one of them goats ain’t got but three legs. Oh, whatever you do, blow the horn three times when you drive up so we’ll know it’s you, not those pesky Joe Ho’vers Witnessers. We all lay down on the floor behind Granny’s old settee when they come a knockin’.”
True story…sort of.
Anyway, to this day, driving on dirt and gravel roads takes me back to the day when unpaved streets and roads were sometimes my best friend when trying to follow a criminal’s trail. Dirt, mud, grass, and even sandy soil can be quite telling…if you take the time to look. Here are a few things investigators look for when following a trail.
1. Both cars and trucks sometimes lose traction when heading uphill, and when they do the tread patterns aren’t clear. When going downhill, tread patterns usually remain unbroken (clear) because the rubber maintains full traction with the surface. Therefore, investigators can easily determine the vehicle’s direction of travel.
2. When viewing tire tracks in the grass it’s important to note whether or not the tracks are shiny/glossy, or not. Glossy tracks mean the vehicle was heading away from the spot where you’re standing. Off color, or slightly dull tracks indicate the vehicle was heading toward your position.
3. When traveling on slightly muddy surfaces (about the consistency of slush), the vehicle’s tires force (squirt) mud forward at a +/- 45 degree angle.
4. Mud puddles, small creeks, etc. are perfect for telling which direction a car or truck is moving. Vehicles always push and pull water in the direction of travel. The liquid also washes away tracks on the exit side of the water. So, if you see a puddle with clear tracks leading up to the water’s edge, and no tracks and a wet surface on the opposite side of the puddle, then you know the vehicle was traveling toward the wet road surface. You may also see wet spots on the dirt road from where water dripped off the car frame, after it passed through the puddle.
5. Wet soil often sticks in the grooves of a tire tread pattern. As the vehicle moves along, the soil begins to dry and falls off, and it always does so in the direction of travel. Investigators can follow the trail much like following a trail of breadcrumbs.
6. When viewing tire tracks always position yourself where the track is directly between you and the sun. This enables the best view of the track’s details.
The same is true for examining footwear impressions.
6. Be sure to photograph the track for later comparison to a tire or shoe.
Finally, as you travel, be sure to examine the sides of the roadway and down paths and trails for the suspect vehicle. It would be pretty darn embarrassing to discover you’d passed by the crooks who’d parked in Mable Johnson’s driveway to count the stolen loot.
They have many names and assorted packaging styles. Some are used in one area of the country while others are used elsewhere. They’re often called by their official given names, but many refer to them simply as “rape kits.”
No matter what they’re called, Physical Evidence Recovery Kit (PERK), Sexual Offense Evidence Collection kit ( SOEC), Sexual Assault Victim Evidence kit (SAVE), they’re all designed for one purpose. For the collection of biological evidence in cases of sexual assault and rape.
Typically, when a victim of sexual assault comes to the hospital, an exam is conducted by a specially trained forensic nurse. The victim will also be seen by a physician. First, the medical experts will make sure there are no life-threatening injuries. Then they’ll ask questions about the assault, health history, medications currently taking, etc.
Next comes the actual physical exam conducted by the forensic nurse, including the collection of the victim’s clothing (in the area where I worked the hospital provided new, clean sweat pants and t-shirt if the victim didn’t bring extra clothing), DNA swabs, hair samples, including a combing of pubic hair to collect possible samples left by the attacker. Blood samples are taken, especially if the victim believes she/he may have drugged as part of the assault. A number of hair samples from the victim are also collected.
Victims may refuse any part of the exam, and they may take a break at any time. They may also elect to NOT report the assault to police.
The collected evidence is placed in various pre-packaged containers provided in the evidence collection kits (rape kits). Kits contain items such as swabs, white sheets (placed beneath the victim during the exam), bottles and plastic bags.
In my jurisdiction, the hospital kept a supply of PERK kits in their inventory. The PERK kit is the evidence collection kit authorized by the Commonwealth of Virginia. This is not the case in all states. Please check with authorities in the area where your story is set if you desire to use an actual name as opposed to “rape kit.”
SAVE evidence collection kit – Arrowhead Forensics
SAVE evidence collection kit – Sirchie
FYI – officers DO NOT use the term “rape kit” when around victims of sexual assault and rape. To do so is extremely insensitive, which is why officers in Virginia refer to the kits as PERK kits.
In the meantime, police are busy collecting evidence elsewhere—bedding (sheets, pillowcases), suspect clothing, and the suspect, if identified and located. Sometimes police take an entire mattress as evidence.
Once the forensic nurse completes the exam the evidence recovery kit is sealed and delivered to the lab for processing, which can take many weeks to complete depending upon backlog.
Many writers have asked about the length of time DNA evidence remains viable in sexual assault cases, and where it can be found. Here’s a handy rule of thumb guide. Remember, various circumstances could change or alter these time-frames.
1. Vaginal DNA samples – up to one week.
2. DNA from skin contact – up to two days. If, for some reason, the victim has not bathed it is possible to obtain a suspect’s DNA sample up to a week later.
3. Oral swabbing with positive results – up to two days.
4. Anal – three days.
5. DNA from suspect’s penis – twelve hours after the assault.
6. DNA from fingers in vagina – up to twelve hours.
*By the way, semen can be detected on clothing despite washing. Remember, though, it is possible that DNA can be transferred from one item to another during washing. This is called tertiary transfer.
Those of you who attended Dr. Dan Krane’s presentation at the Writers’ Police Academy may recall when he described how this is possible. In fact, as a world-renowned DNA expert, he’s testified about tertiary DNA transfer in high-profile court cases.
Therefore, writers, it is possible for a DNA sample to show up on the clothing of completely innocent person, such as the unsuspecting roommate who shares a load of laundry with his buddy the psycho- serial rapist. How’s that for a plot twist!
*Thanks to Wally and crew over at crimescenewriter for the topic idea!
When investigators find maggots on a body that are in their early larvae stages, say…oh…when they’re 5mm in length, well, officers will then have a pretty good idea that the victim has been there for only a day and a half, or so.
Even the mere presence of certain insects is quite telling.
Now, please do enjoy your Thanksgiving dinner!
“Yes, Watson, you heard me correctly. The murder weapon was indeed a cute, fluffy bunny.”
“Don’t be silly. Of course she didn’t bludgeon the man to death with the animal.”
“No more speculation, please. Here’s how she did it…”
Tularemia, or rabbit fever as it’s commonly called, is no stranger to the United States. After its discovery in 1911 in Tulare, California, the disease became known as a killing machine. It killed a large number of ground squirrels before finding its way into human bodies where it infected hunters and other outdoorsmen, and any others who came into contact with infected animals.
Today, the Center for Disease Control (CDC) reports roughly 200 cases of Tularemia (Francisella tularensis) each year in America. Only about two percent of those cases are fatal, but, since it is possible to transform the tularemia microbe to an aerosol form, the plague-like disease could be used as a very effective biological weapon.
Killers in mystery novels might find tularemia a most effective way to murder their victims, since pathologists and toxicologists do not routinely screen for it during autopsy. And, Tularemia is not easily detected by doctors.
Tularemia-carrying organisms are readily found in wild animals—particularly feral rabbits—in their feces. It’s also found in water and mud. Humans can contract tularemia by handling the hides, paws, or flesh of wild rabbits. They can also catch the disease by eating undercooked rabbit meat. Ticks, mosquitoes, and deer flies can transfer the sickness to humans through their bites.
A hunter with an open cut or wound can contract tularemia simply by skinning a rabbit. A murderous spouse could introduce the bacteria into her unsuspecting hunter-husband’s food (Tularemia-tainted meat), then blame the death on the infected rabbits the sportsman shot during his hunt. The wife could easily explain the symptoms away until her husband was too far-gone for medical help. The disease offers a variety of symptoms, depending upon the way it is introduced to the victim. Inhaled tularemia, the method most likely to be used by terrorists, presents flu-like symptoms—fever, chills, loss of appetite, cough, and headache. Swollen lymph nodes, skin ulcers, and pneumonia can accompany these symptoms.
Certain strains of tularemia are currently incurable because they have been genetically engineered to be antibiotic-resistant. This disease, though deadly, cannot be spread by human-to-human contact.
The use of tularemia in germ warfare is not new to the military. In 1932 and again in 1945, the Japanese studied using tularemia as a possible biological weapon. Thousands of Soviet and German soldiers serving on the Eastern front during WWII succumbed to tularemia. There is some speculation that the disease was introduced to them intentionally.
The U.S. also developed and stockpiled tularemia (by freezing). The military conducted tests on the agent (code named Agent UL) by spraying barges containing monkeys in the waters off Hawaii. The spray was introduced by aircraft over several miles. As a result, over half the monkeys were infected with tularemia. Approximately half of the infected monkeys died.
An American fell ill with Tularemia when he ran over an infected rabbit while mowing his lawn. It was this instance that cemented the fact that tularemia could be contracted by inhalation. In 2000, an outbreak of tularemia occurred on Martha’s Vineyard. The cause of the outbreak…lawn mowing. In 2003, a Nantucket maintenance worker ran over an infected rabbit with his lawnmower, however, it was not he who contracted the disease. Instead, it was a co-worker who used a stick to remove the animal to nearby bushes.
Terrorists can transmit the bacteria either in food or by an aerosol propellant. Large numbers of people could be infected at once with only a microscopic amount of the bacteria.
So, what have we learned from all this? That’s right, be vewy, vewy quiet when hunting wabbits…
Warner Brothers image/public domain
* Top photo by Luis Miguel Bugallo Sánchez – Wikimedia Commons. Second image Sidney Paget/public domain
Every good thriller has at least one big explosion, right? You know, the “big boom” that always takes place right after the heart-stopping car chase, just before the hero rescues the kidnap victim who’s about to die at the hand of the cleverly-written villain. Yes, that explosion.
What we don’t see in our favorite thriller, though, is the collecting of evidence at explosion scenes. So let’s take a moment to examine that aspect of the scenario. What should be happening in the background while the hero is saving the world?
1. Bombings/explosions are not for the Sam Spade’s of the police department. Nope, these crimes should be worked by specially-trained investigators, as well as a team of experts that includes (but is not limited to) bomb disposal technicians, photographer, forensics/CSI team, medical examiner (if needed), structural engineer(s), building safety official, power company technician, additional officers to help search, etc.
2. Bombing scenes are apt to change at any moment (parts of a building may suddenly collapse, etc.), therefore, the investigator must be constantly aware of the surroundings, and he/she must thoroughly evaluate and re-evaluate before allowing evidence collection to begin.
3. As always, the scene should remain secure. A command post should be established, as well as a secure and safe location for staging collected evidence.
4. Locate and dispose of all remaining active explosives, utilizing canines, bomb robots, explosive detection chemicals, etc.
5. To avoid contamination, the team should wear protective clothing as they collect evidence and control samples. The special clothing also protects the investigator’s skin from toxic material.
6. Evidence from various locations at the scene should be stored separately (do not mix).
7. Collect ALL evidence, including suspected bomb parts, batteries, wires, samples from crater, and the usual hair, fibers, blood, etc. During autopsy the medical examiner will also collect fragments removed from victims,
8. Document the scene—blast effect (are street signs leaning away from the blast scene? if so, indicate direction. trees down? cars overturned?), debris (type, amount of, and distance from the blast site), victim(s) location before and after the blast occurred.
9. Medical examiner should conduct full-body x-rays, searching for components of the bomb and other foreign material relevant to the crime.
10. And, without fail, the investigator should always…walk softly.
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