forensics

FW: “Have you been fingerprinted?”

August, 2019 note: I had occasion to return to SIRCHIE during MurderCon, a  Writers’ Police Academy event. While the instructors were different, it’s reassuring to note that the science remains the same. Read on for details about gathering fingerprints from paper.

 

People ask me all the time how I acquire the information needed to write Kerrian’s Notebook.

 

Simple answer: research. And lots of it.

 

If the questioners want to know more, I mention the conferences I attend, the reference books I read, the internet sources I’ve tapped into, and the experts willing to chat about their chosen fields. It’s a fascinating part of the job and I love it.

 

The next few posts will reveal some of the information gathered at a series of classes where I took photos and lots of notes. If you’re a regular follower of Kerrian’s Notebook, you may recognize some of the details mentioned here as having appeared on previous Detective Kerrian’s pages.

 

For all out fun, I go to the Writers’ Police Academy held in September – this was the 5th year at the Guilford County, NC location (my fourth). It’s a three-day, mind-blowing experience that demonstrates the nuts and bolts of police and fire and EMS procedure – taught by professionals and experts actively working in the field.

 

Along with several other strands of study, the 2011 WPA conference provided classes in bloodstain patterns, fingerprinting, and alternate light sources (ALS) conducted by Sirchie instructors. Because of the standing room only enthusiasm for these classes, Sirchie offered a five-day Evidence Collection training session for writers at their own complex in North Carolina. Sirchie makes hundreds of products for the law enforcement community and I felt this would be a great opportunity for Detective Kerrian to learn more about the latest and best gadgets being used to catch the crooks.

 I happily sent in my application and plunked down my credit card to hold my space in the class – ten months ahead of time.

 

On the first day of classes, our instructor, Robert Skiff (Training Manager/Technical Training Specialist at Sirchie) discussed the ‘CSI Effect’ – the pressure placed by the popular TV shows on real life crime investigation. TV labs and real life investigations bear little resemblance to each other – not in time, or equipment, or budgets. Then we got to work, using the powders and brushes needed to process a crime scene and used by actual techs in the lab.

Fingerprint powders, brushes and magnifier

It’s up to investigators and examiners to prove the case against the suspects, using proper evidence collection techniques and tools, because trace evidence is ALWAYS left behind.

 

Fingerprints found at the scene are still the favored piece of evidence tying the suspect to the crime. These days, using a combination of ingenuity and newly developed chemicals and powders, a crime scene investigator can lift (and/or photograph) prints from many previously challenging surfaces. 

 

By the way, black fingerprint powder gets all over everything when newbies are handling it for the first time. We must have used 50 wet wipes each during the morning alone.

 

After dusting prints with black fingerprint powder,

 

they were lifted from various smooth surfaces using (in forefront) a gel lifter, a hinge lifter and (in background) tape.

 

We had to be careful not to contaminate the powders and jars or smear the samples themselves before looking at the prints under the magnifier. By the end of the day, most of us had black eyes and streaks on our hands and faces. It looks much easier on TV.

 

Our prints were photographed and then viewed under an Optical Comparator. This machine can be hooked up to a laptop, and the image sent off to AFIS for identification purposes. No crooks in our crowd, so we omitted that step.

 

At the end of the first day we left happy, tired, and still wiping powder off our hands and faces. A tip from an investigator taking the class with us: add a cup of vinegar to the wash load to get those powder stains out.

 

Did I mention that we had loads of fun?

 

On the second day, Robert Skiff’s assistant for the class, Chrissy Hunter, passed out stainless steel rectangles and we pressed our fingers onto the plates, twice. First time – plain ole print, second time – ‘enhanced’ by first rubbing our fingers on our necks and foreheads to increase the amount of oils in the print. The ridge detail in the prints was so clear in the ‘enhanced’ version that there was no need to process them with powder. We lifted them with a gel lift.

 

If we were working a real scene, that might never happen, but it could. The usual occurrence is that partial prints are left at the scene and that’s what makes the search for the suspects so much tougher than what the TV dramas indicate. There is no instant ‘a-ha’ moment that comes 45 minutes after the crime has been committed.

 

The prints are generally sent off to be compared with the millions in the AFIS database, and here’s where TV parts with reality again. AFIS comes back with a list of 10-20 possible matches and someone then makes a comparison by hand of the most likely hits.

 

After practicing the basics, it was time to move on to fingerprint discovery on documents. There are scheming relatives who forge wills, less than loving spouses who murder for the insurance, bogus suicide notes, and the list goes on. How to prove the nefarious intent? Fingerprints. But…as we discovered the first day, fingerprint powder is messy and almost impossible to clean up. An important document could be destroyed in the search for evidence of foul play. Enter chemicals and alternate light sources (ALS).

There is a protocol for testing with chemicals. If the prints don’t show up with one chemical, then it is possible to try several others, but this can only be done in a certain order:

 

Iodine

DFO

Ninhydrin

Silver Nitrate

MBD

 

If used in this order, the sample won’t be compromised, even though treated several times over several days. We experimented with several chemicals with excellent results, but for the ‘wow’ factor, I’m showing the ones that look great on camera.  😉

Spraying Document

 DFO reacts to amino acids in the prints. We created our samples placing our own enhanced prints on plain white paper. We hung the papers in the fume hood, saturated them with DFO, then put them in the oven to bake for several minutes.

This DFO sprayed, baked sample doesn’t look like much, so it was time to use an ALS to really ‘pop’ the print and make it photo ready.

Alternate Light Sources vary depending on the scene lighting and/or need to highlight the evidence. A few used in the field are: the ‘poor man’s ultimate light source’ (a mag light), black lights, UVC lights, lasers, LED lights, Ruvis lights (cost about $20K), and pure white lights. Each has a specific quality that the investigators can tap when needed.

After we sprayed our samples with DFO and baked them in the oven, we darkened the room, and put on orange plastic glasses. Then we side-lit the sample with a 455nm light. The photo was taken at that point.

Same sample, side-lit at a slightly different angle. Photo taken through an orange filter.

 

Ninhydrin, the third chemical group in the list to be used if nothing has shown up yet, comes in several forms: acetone, zylene and Noveck.  Ninhydrin reacts to another set of amino acids and likes warm, moist air. If a sample is being saved overnight for processing, you can place it in a ziplock bag, blow into it, then seal it and still maintain its integrity.

 

Before working with any chemical, it’s a good idea to make copies of the document. Why are there different kinds of Ninhydrin? Zylene will run some inks. Acetone will run all inks, all the time. Ooops! There goes the document if you grab the wrong chemical, so copies are definitely necessary. Noveck is the clear winner when working with inks. It gets fast results and dries quickly. Additionally, it can be sprayed on an outer envelope to reveal what’s inside. Without damaging either piece of paper. Very cool.

Ninhydrin-Noveck sprayed on outer envelope

 

You could see the plots developing in our writerly minds as the Noveck dried and the words inside the folder faded from view.

 

 

 

 

*Photos taken by Patti Phillips at the Sirchie Education and Training Center in Youngsville, North Carolina.

 

 

 

KN, p. 82 “Is that your footprint?”

 

 

 

 

It’s been raining off and on for days. It rained last week during a party, and people were tracking water and a little mud from the driveway runoff onto the porch all afternoon. We had so many different kinds of footprints that it would have made for a great crime scene demonstration.

 

Because, one of the most overlooked pieces of evidence at a crime scene is created by footwear.

 

Imagine: If a window breaks as a thief enters the premises during the commission of a burglary, the glass will fall into the house, and onto the floor or rug below the window. When the thief steps through the window, unless the thief has wings, he/she will probably plant a foot right in the middle of the glass. And walk through the house, most likely tracking minute pieces of that glass. That glass may also become embedded in the grooves of the sole of the shoe, creating a distinctive footprint.

 

If the investigating officer can place a suspect at the scene with the footprint, then there is probable cause to fingerprint that suspect and hopefully establish a link to the crime.

 

A new method of eliminating suspects right at the scene involves stepping into a tray that contains a pad soaked with harmless clear ink that doesn’t stain, then stepping onto a chemically treated impression card. No messy cleanup, immediate results, and it can even show details of wear and tear on the shoe. This can be a way to establish a known standard (we know where this impression came from) to compare with multiple tread prints at the scene.

Footwear Clear Ink Impression

 

 

Another tool for creating a known standard is the foam impression system. It takes a bit longer, (24 hours) but clear, crisp impressions can be made, including of the pebbles and bits stuck deep into the grooves and the writing on the arch. Very helpful when trying to place suspects at the scene. A rock stuck in the sole is a random characteristic that can’t be duplicated, so becomes another point of identification.

 

This is how it works: Somebody steps into a box of stiff-ish foam – a bit like stepping into wet sand.

 

An impression is made instantaneously. The detail is great – down to the wear on the heel.

Pre-mixed dental stone (made with distilled water and the powder) is used to fill the impression.

It takes 24 hours for the cast to become firm enough to pop out of the foam. We now have a permanent record of the footwear tread, which could be used for comparison to other prints found at the scene.

Footwear Casts

 

Occasionally footprints are found on the ground outside a window or in the gardens surrounding a house after a burglary or homicide. Ever see a crime show on TV where the fictional investigator makes a snap judgment about the height and weight of the owner of the footprint because of the depth of the impression? That’s merely a plot device and is not scientific evidence in real life. A crime scene photographer or investigator can photograph the footprint (next to a measurement scale), make a take away cast, and then compare the impression with those of the suspects or other bystanders at the scene. Beware: making a cast of the print destroys the print, so a photograph must be taken before pouring that first drop of dental stone.

 

Footprints can be found at bloody crime scenes as well. The suspect walks through the blood, tracks it through the house, cleans it up, but the prints are still there, even though not obvious to the naked eye. Blood just doesn’t go away, no matter how hard you try to get rid of it. It seeps into the cracks and crevices of a floor and even behind baseboards.

 

A savvy investigator will collect sections of carpet (or flooring) taken from where the suspect might have walked during the commission of the crime, then conduct a presumptive test for blood (LCV – Aqueous Leuco Crystal Violet), find a usable footprint, compare it to a known standard, and then be able to place the suspect at the scene.

 

 

 

 

Be careful where you walk. That footprint can be used as evidence.

 

 

 

*Photos taken by Patti Phillips

 

 

 

 

KN, p. 141 “What does a CSI tech really do?”

 

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:

 

  • Consultation on the value, use, collection, and preservation of evidence,
  • Analysis and comparison of evidence from crime scenes and/or people,
  • Expert testimony in court proceedings, and
  • Assistance for collecting evidence and processing crime scenes,
  • Forensic science information to law enforcement agencies and district attorneys.

 

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:

 

  • Fingerprints
  • Blood spatters
  • Fibers
  • Footwear impressions
  • Tire impressions
  • Tool impressions
  • DNA samples (hair, nails, blood, saliva, etc)
  • Murder weapon
  • Point of entry
  • Kinds of items taken

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

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