Mike ByrdMiami-Dade Police DepartmentCrime scene Investigations

Many very good articles and also books have been written on fingerprint technology. For the crime step investigator or proof recovery technician assigned the task of recovering fingerprint impressions in ~ the crime scene, it is essential that they have a great solid foundation of the straightforward knowledge. The expertise should incorporate the basic terminology, the tools that is easily accessible , safety standards because that the products being used and the basic skills that room being applied in the field.

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Fingerprint identification

In criminal investigations fingerprints are among the oldest and most common species of physical evidence uncovered at a crime scene. One of the main goals that the investigation encounters identification. Even if it is the identification is the of an unknown victim (body uncovered at the next of the road) or that of the perpetrator the a crime. The ridge information developed and recovered in ~ a crime scene and also later established by a fingerprint examiner i do not care an investigative lead (starting point) because that the detectives assigned come the investigation. A fingerprint is simply defined as friction ridge information of the hands and the feet. The friction ridges serve two basic purposes. An initial they allow us come grip and also hold ~ above to assorted surfaces. In forensics, they serve as a method of individual identification.

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Fingerprints and The Crime scene Investigator/Technician

Departments and also agencies transparent the nation vary as to whom is assigned the duties of handling the crime scene and recovery that the latent impressions.

The goal of the crime step investigator or evidence recovery technician is recognition and recovery of friction ridge information that can be deposit on the many different surfaces at a crime scene. The crime step investigator/technician must have actually an knowledge of the species of ridge information that might be deposit on the scene, the types of surfaces that would retain the detail, and also the techniques used in recovering those deposits. The biggest an obstacle for an innovation today is adopting to save up through the ever-changing surface ar materials.

Categories that prints

Different areas of the country have various phrases offered to explain the terminology and also techniques in ridge information deposit and also recovery. There are three an easy categories or species of impressions that might be deposited, detected, developed if require be and also recovered in ~ a crime scene.

1. Latent

The skin has deposits that oil and perspiration that typically coat the surface. As soon as the hand touches the surface, some of the moisture is transferred from the hand come the object, leave an impression that the friction ridge detail. These are described as latent impressions. On most surfaces the latent impressions space not readily visible. The word latent is defined as not visible. That does not typical that that is in reality invisible. Using obtainable or oblique lighting on most surfaces will expose the impression. The impression have to be intensified or occurred to be seen completely and collected.

2. Patent

A patent impression occurs together the result of transporting a foreign material coating the skin of the fingers. Examples of the foreign material would certainly be substances favor paint, tar, grease, blood, or ink. The best example that a patent impression would certainly be the ink criter or elimination"s the we as investigators collect from individuals. After ~ the squid is applied it becomes the foreign material coating the hands of the individual. A map is supplied as a transport medium, thus ending up being the thing touched and a transferring of the patent impression takes place. Words patent method obvious or evident. Patent impressions are visible and also usually need no enhancement. Lock are just photographed and also the item that they space deposited ~ above is collected if necessary. The photograph and also or object in reality becomes the investigators lift.

3. Plastic or Molded

A plastic or molded impression is deposited when the hands, fingers, or feet is pressed into a soft rubbery type material that will retain the impression that the ridge detail. Whereby a implicitly impression is deposited on the surface, a plastic or molded impression would be deposited right into the surface. Examples of the products where a plastic impression would certainly be deposited are clay, wet repaint , blood, or tar. Plastic or molded impressions are visible and also usually need no enhancement. They are simply photographed and if essential the item is gathered and may have actually the ability to be caste.

As a more example; If us were to ask the question, "Is a bloody publish the same as a publish in blood" ? The answer to this concern would be, "NO". The publish in blood would be an instance of depositing a plastic or molded impression into the surface ar of blood. The bloody publish would be an example of having actually a international substance, such together the blood, coating the hand and depositing one impression from the blood coating to an additional surface.


The discovery procedure or visual find for a implicitly impression starts at a point of entry and works the way into and surrounding the crime scene. The search is to discover items that have actually been handled, moved or anything that appears out that place. The most perfect surfaces room smooth, hard, non-absorbent and also non-porous surfaces. Patience, typical sense, and experience are essential to assure that all latent impressions space collected. Ongoing practice will provide the confidence necessary to collection all varieties of impressions from various surfaces.


In recovering implicit impressions there are plenty of products accessible for the task. The techniques can be broken down right into four simple areas. The conventional techniques consist that mechanical and chemical development. The more modern-day techniques applied today in recovering latent impressions space florescent die stains or powders (aided v some type laser or light source), and superglue fuming. It need to be noted that implicit impressions on some surfaces may be fragile.

Mechanical Development

Mechanical development is the usage of a brush and also powder to physically dust the surface. This technique allows the corpuscle of the flour to adhere to the contaminates which causes the ridge deposits. The mechanical breakthrough is for nonporous items and surfaces.

There are three species of brushes manufactured for the usage of mechanical ridge detail development:

FiberglassCamel hairFeather brush

There space an assortment the powders, lifters and also tapes that room specially formulated and manufactured because that the usage of impression recovery.

ChemicalFor protection and also safety factors these techniques are used in the activities under fine ventilated conditions. A range of chemistry are produced to react to specific components that comprise the ridge deposits. Much more than a general knowledge the the chemicals and also the contaminates in the deposits are required to execute these tasks. The chemistry processing techniques are because that porous, absorbent items such as paper, untreated wood, and also matte, semi-porous finished items.Superglue Fuming

Cyanoacrylate ester is the energetic ingredient in superglue. It creates a vapor that polymerizes (creates a white residue) ~ above contaminates such as latent impression deposits. Superglue is sold in a liquid or pouch form and comes in a selection of viscosity"s. As documented by the US army Crime Lab, superglue fumes space strongly irritating to the eyes and respiratory system. Personal Safety and caution room the keys to this advancement technique. The main purpose of superglue in the field is to deal with the impression ~ above items whereby the latent impression might be fragile, so that it is less destructible throughout processing or transport. The does no make the impression indestructible. There is no the suitable caution the impression deserve to still it is in wiped away or destroyed.

Contributing factors and conditions for deposit and also recovery

These problems contribute not just to the depositing that the ridge information but likewise to the advance and recovery stages.

Nature and also cleanliness the surfaceEnvironmentWeather conditionsAmount the contaminantPressure appliedMovement during transferCondition that the friction ridge detail


After developing the implicitly impression the is lifted through a clean tape or lifting medium and placed on a backing card through a difference background. The area where the lift was taken indigenous is documented on the ago of the card together with the instance number designating it come a details investigation, the name and also identification variety of the investigator lifting the impression, and also the day of the lift. The integrity of the elevator is kept by the investigator"s/technician"s initials, a seal is produced by the initials placed fifty percent on the ice that has the lift and half on the map itself. To present no tampering has occurred.

Many Departments have a policy that each latent impression it is in photographed before being recovered. This is done largely as an orientation to show the article the implicitly impression to be recovered from, and as a safeguard simply incase the implicitly impression is lost or damaged during the recovery stages. The investigator/technician should follow his/her departments details policies in this action.

Safety and Do"s and Don"ts

Remove any kind of excess powder from the surface ar of the occurred impression before using the lifting tape. This deserve to be excellent by punch on the surface, utilizing a small can of compressed waiting or to brush lightly in opposing direction over the area . This assures a clean lift through no waiting pockets (fish eye). Air pockets room the tiny bubbles that air the hinder the tape from being smoothly used over the surface. The air pockets are caused by overabundance powder and also other debris on height of the surface.

Wear a respiratory tract (dust) mask, gloves and also eye protection once working with powders of any type of kind because that a an extensive periods. That is essential that the investigator/technician be mindful of the tools that they room using in the field and also in the lab. The Manufacturer security Data paper (MSDS) is available with all products and also should be check out on any items supplied by the technician/investigator. This will assure the the investigator is conscious of any type of potential safety danger that might exist v the commodities being used. Safety must be the optimal priority because that the investigator.

Never organize the bristle part of the brush. The brush should be totally free of any oil or contaminates. This assures the technician/investigator does not have a brush with hardened bristles that will rub the end or ruin the print.

Never with up to apply powder to an item above you. Usage a ladder or step stool to save the processing procedure listed below eye level. Small powder particles may reason irritation and/or epidemic to the eyes.

A keep in mind from the author, Mike Byrd: I have actually facilitated much more than 100 8-hour workshops in crime scene recognition and also latent impressions recovery due to the fact that 1988. Throughout each workshop ns have gained some brand-new knowledge from my students. There is a incredible pleasure in understanding that experienced students have walked far from those workshops v refreshed ideas along with enhancing the skills which they had currently developed. Very first time students have actually walked away through the solid structure of basic skills ideas needed for success and also confidence.

About the Author


Mike Byrd (1955-2005) joined the Miami-Dade ar Police department in 1983 and also started with the Crime scene Investigations office in 1987. He took an exceptionally active component in the science of forensic crime step investigations, including advancement of brand-new techniques, posting methodology the crime scene procedures, and also teaching. Mike developed brand-new techniques because that gathering and cataloging crime scene evidence including the lifting of fingerprints, vehicle tire impressions, and also footwear impressions.

Mike"s approaches and analysis withstood the scrutiny the the criminal righteousness process. He published more than thirty crime scene articles on crime scene evidence collection and for the global Association for Identification and also was vested The good of the combination Award in 2002 because that his innovative to know methodology and also techniques. He teach crime scene investigation procedures and also techniques in ~ police departments roughly the country and also took great pride at instructing smaller Florida police departments in the latest approaches in evidence gathering.

Mike carry out the tough detailed oriented forensic job-related at many significant crime scenes and also disasters end two-decades. He gathered, processed, and identified the DNA evidence used to judge the Tamiami Strangler because that a wire of heinous murders in 1994. His thoughtful gathering of evidence at the Valujet crash allowed families to reach closure because that the deaths of love ones.

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Mike Byrd died after a much more than 2 year battle with many myeloma cancer. Annually, the Police Officer aid Trust awards the Mike Byrd Crime Scene examination Scholarship in his honor.