forensics

FW: “Quick! Grab the glue gun!”


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

Part 4 – “Quick! Grab the glue gun!”

 

Wet Lift Print as seen on a Comparator

We often hear it said on TV and in the movies that there are items and surfaces that do not hold fingerprints or that fingerprints cannot be recovered from them. On Day #4 of the Sirchie Evidence Collection Training Classes held at the Sirchie Fingerprint Laboratories in NC, we experimented with a variety of surfaces to see what would happen if…

 

Skin is reported to be one of the most difficult surfaces from which to lift a print, because the prints fade so quickly. But, after three days of dusting and chemically treating and lifting and photographing dubious fingerprints, our group of dogged writer/investigators was not to be deterred.

 

The set of prints in the photograph below were lifted from an arm. Not clothing, the arm itself. And not by using fingerprint powder on the arm. A classmate kindly offered up her arm to be grabbed. Then a piece of specially treated paper (chromicoat) was pressed onto the area of her arm where the fingerprints were likely to be found. That paper was then dusted with fingerprint powder and the prints popped up. We now knew it was possible to lift the prints if they were minutes old, but we had access to both the specially treated paper and the powder immediately after the grab. We also knew from experience that our grabber always left really good prints on all the surfaces touched during the previous days.

 

Lift from skin using Chromicoat treated paper

We proposed various scenarios to our instructor (equally curious Robert Skiff, Sirchie Training Manager/Technical Training Specialist). What if a mugger grabbed a bare arm and tried to drag us into an alley? How close would we have to be to the police station after we got away from the mugger in order to get the prints processed? How much time did we have before they faded away? Would the lift work if we used plain paper, since it was highly unlikely that an ordinary gal would be carrying chromicoat paper in a pocket? What if the police station wasn’t close by, therefore no access to fingerprint powder?

 

The answers were time sensitive. It was possible to lift prints from a bare arm with plain paper, but only if the lift was made during the first few minutes and only if the suspect left a strong sample. It’s possible to use cigarette ashes as a substitute for the fingerprint powder. Conclusions? There were too many variables for this to be a reliable way to catch a crook. Now…if you were grabbed around the corner from a police station OR were a smoker AND the mugger had dirty hands AND you had a clean piece of paper in your pocket AND you had attended this class… Hmmm…maybe in a sci-fi mystery. However, not completely impossible.

 

Another difficult surface from which to lift prints is the dashboard of a car. Think about it. If you press your hand onto a dashboard, your skin (with all the loops and whorls and arches) is also pressing into the crevices of the pebbled surface. Same thing is true for an orange or a football. A straight gel lift or hinge lifter will not do the job effectively. A tape lift 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

 

Another tricky scenario: The cop is in pursuit of an unidentified car thief or robber and chases him through a parking lot.  The cop witnesses the suspect firmly planting his palm on the trunk of a car as he cuts through a tight space. The cop grins as he realizes that even if the guy outruns him, he can catch him through the palm print. And, then, it starts to pour. Does the print get washed away? Or become unusable?

 

Not if the Field Kit is handy! When forced to do a wet lift, it is possible to use SPR (Small Particle Reagent – finely ground particles suspended in a detergent solution). Spray the print with a fine mist of SPR and let set. Lay the hinge lifter just off the print and place it down carefully, employing a squeegee at the same time, to slowly remove the excess water. This method can be used to develop prints on non-porous surfaces – cans, bottles, windows, and other glossy surfaces, but not on paper or cardboard.

 

Wet Lift Prints

 

 

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 he 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

A 2% chloroform tape release agent is dropped liberally 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 are folded over (about ¼”) and the tape is flattened for 24 hours before further processing.

 

Adhesive-side developer

After 24 hours, adhesive-side developer is applied to the sticky side of the duct tape, allowed to sit for a few minutes, then rinsed off and voila! The prints are clearly visible, can be photographed, covered with clear tape to protect them, viewed under the Optical Comparator, entered into the system, and sent off to AFIS.  (Crystal Violet can also be used for processing this type of print, but is toxic and should only be used in a lab.)

 

Duct tape prints

 

AFIS – what is it and does it really help identify a person of interest in a crime?

 

Anyone who has watched TV crime shows during the last decade has heard the acronym AFIS. It stands for Automated Fingerprint Identification System.  In 1924, the FBI started a fingerprint identification system. They fingerprinted several thousand prisoners incarcerated at Leavenworth, and stored their prints on cards.

 

As of 2012, the system had broadened to include international prints as well, is an electronic database of 70 million, and contains the prints of both law-abiding citizens as well as those of criminals. While newborn babies are printed, their information is usually entered into a local system unless needed in an abduction case. Real estate agents, childcare workers, Federal employees, and people seeking employment with security and law enforcement agencies are fingerprinted as a matter of course now. Depending on the State, the prints are entered into the State AFIS system, and held until needed in the national system. The fingerprints of any person arrested for any level of crime are sent to the State and then on to the national FBI database. The latest FBI version is named IAFIS (I is for Integrated).

 

Johnny Leonard, a latent fingerprint expert, visited the class in the afternoon to explain what AFIS can and can’t do. He showed us what a fingerprint examiner looks for in every print or partial print he/she sees, using the Henry Fingerprint Classification and Identification method. The average number of minutiae on every complete print is between 100 and 150. There are distinct ridge patterns to look for in a print: arches, loops and whorls.

 

Fingerprint Loops

65% of all fingerprint patterns are loops,

 

 

Fingerprint Whorls

30% are whorls,

 

 

Fingerprint Arches

and only 5% of fingerprint patterns are arches.

 

Thumb prints are the prints most often left at a crime scene, because people use their thumbs for leverage when pushing through doors or opening safes, or grabbing those golf clubs to use as weapons, etc.

 

Identifying 8-12 points of similarity between an unknown latent print found at a crime scene and one in the AFIS database is the standard for declaring a match, but some jurisdictions want more for absolute certainty.  An examiner plots the print in question for distinct characteristics, makes notes to that effect before sending the print off and waits. AFIS & IAFIS return a list (sometimes as many as 30) of possible matches. At this point, the examiner reviews the possibles and chooses the best match in his/her opinion. And, it might not be the first on the list. Then, another examiner verifies the possible match. There is no such thing as an instantaneous match with just one print from the AFIS or IAFIS databases. TV tells us otherwise, but sorry, that’s merely for dramatic effect.

 

Other interesting fingerprint details:

*We know that no two people can have the same fingerprints, but not even the same person’s prints are identical.

*Some people have all three types of ridge patterns on one finger.

*Only positive matches from the state AFIS are verified by examiners; not the negative ones.

*Palm prints are now in the AFIS database.

*AFIS looks for change of direction in the whorls, loops, and arches in order to find a match.

*There has not been a case yet where the DNA has not matched the fingerprints at the scene.

 

 

The photo below shows a positive match between a latent print and one in the database. The latent is on the left. The database print is on the right. This match placed the suspect at the scene and along with other evidence, resulted in a conviction.

 

AFIS match

 

Having been through four days of training, working with prints on a variety of surfaces, we felt confident that we were up to the challenge of matching a few fingerprints on our own. Mr. Leonard showed us 16 pairs of prints and gave us 15 minutes to make decisions. We looked for cluster highlights, tented arches, spots, bifurcations and other techy details. Guess what? The lines began to blur, and not all of us correctly identified all the matches.

 

TV makes it look easy, with a click and a less than five-minute response time from IAFIS. Not possible, with 70 million fingerprints to choose from. This is not an easy job, even with the new digital readers that speed up the process of finding likely matches at the scene.

 

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

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

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

 

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

 

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.

 

 

KN, p. 218 “What Does the Federal Bureau of Investigation Do?”

 

“The Federal Bureau of Investigation (FBI) is an intelligence-driven and threat-focused national security organization with both intelligence and law enforcement responsibilities.”*  It is the chief fact-finding branch of the Department of Justice and helps other agencies by sharing that information and providing training.

 

Its mission is:

“To protect the American people and uphold the Constitution of the United States.”*

 

In 1908, the United States had about 100 cities with 50,000 people. The rest of the population (about 83 million) was spread throughout the rural areas of the country. Law enforcement personnel at the local level were often poorly paid (and were sometimes volunteer) members of the community. Murders were handled by local investigators and still are to this day. For the majority of the cases, murder is not a federal crime, unless carried out across State lines.

 

Prosecution of border security issues or organized crime was limited in 1908 since there was no adequate way to enforce the law at a national level. In fact, few criminal laws even existed at a federal level. For the most part, individual States and local jurisdictions handled their own criminal investigations, and sometimes that led to political corruption, corporate criminal behavior, and even slave labor in factories. Federal agencies were stretched thin or were nonexistent in some parts of the country.

 

President Teddy Roosevelt supported the idea of modernizing law enforcement, so when his Attorney General hired 34 of his own investigators (including nine seasoned Secret Service agents) to assist the Department of Justice, Roosevelt wholeheartedly endorsed the action. A few months later, the Bureau of Investigation was officially created. Hardly a large force, but it was a start.

 

At the beginning, incidents involving car theft across State lines, civil rights, and various kinds of fraud were the typical cases. The FBI also took on treason and domestic terrorism, and Congress (previously reluctant to loosen the purse strings) began to see the value of a national law enforcement agency.

 

It’s interesting to note that the Mann Act or “White Slave Traffic Act,” was passed in 1910 to help stop interstate prostitution and human trafficking, and the FBI had a role in the early investigations. One hundred years later, it has become an international problem and requires cooperation from many different agencies to obtain successful prosecutions.

 

World War 1 brought us the problems of sabotage by foreign agents against our military ships and munitions plants, as well as international smuggling. The FBI had entered the so-called spy business and worked hard to eliminate those threats.

 

In 1924, it was recognized that fingerprinting was a reliable way of connecting (or eliminating) individuals to a particular scene, and to collect that information in a central location would be helpful to other law enforcement agencies in the United States. Now, the FBI gathers and classifies fingerprints from convicted felons and other criminals, military personnel, federal applicants and employees, and shares that information with appropriate agencies. Additionally, fingerprints of military detainees and other persons of national security interest are being collected for national security purposes.

 

Formerly called Automated Fingerprint Identification System (AFIS), the program processes over 63,000 prints a day, is now integrated with other forms of identification and called IAFIS, and can deliver digital information in as little as two hours. It is used in connection with biometric databases (facial and voice recognition) for more accurate identifications. Next Generation Identification (NGI) combines biometrics, fingerprints, and palm prints to expand identification possibilities.

 

One of the programs developed by the FBI is the ‘Ten Most Wanted’ list. It began in 1950 as a way to call attention to fugitives who might otherwise remain at large. Each new list is posted in United States Post Offices and on the FBI website.

 

Since 1950, 518 fugitives have been on the list, and 484 have been apprehended or located. The stats below are from the FBI site:

    • 162 fugitives have been captured/located as a result of citizen cooperation.
    • Two fugitives were apprehended because of visitors on an FBI tour.
    • The shortest amount of time on the list was two hours, by Billy Austin Bryant.
    • The longest amount of time on the list was over 32 years by Victor Manuel Gerena.


With the advent of increased world-wide terrorism, the computer and cyber-security age, more complex corporate crimes, and a global awareness of human trafficking, the focus of the FBI has shifted.

 

At the end of 2017, there were over 35,000 employees, made up of intelligence analysts, field agents, language specialists, scientists, and information technology specialists. They are tasked with investigating:

 

  • Terrorism
  • Counterintelligence
  • Cyber Crime
  • Public Corruption
  • Civil Rights
  • Organized Crime
  • White-Collar Crime
  • Violent Crime
  • WMD (Weapons of Mass Destruction)

 

 

Stay tuned for posts about Quantico and training for the FBI, and interviews with former FBI agents.

 

*Photo and quotes credit: (from FBI website)

1969 Latent Print Match
A latent print removed from a 1969 murder victim’s car was later determined to be a match to the suspect’s fingerprint (inset) contained in the FBI’s Integrated Automated Fingerprint Identification System (IAFIS). The Houston police detective and Texas Department of Public Safety latent print technician instrumental in solving the cold case were honored by the FBI with the 2011 “Latent Hit of the Year” Award.

 

 

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