Comparison microscope
Encyclopedia
A comparison microscope is a device used to analyze side-by-side specimens. It consists of two microscope
s connected by an optical bridge, which results in a split view window enabling two separate objects to be viewed simultaneously. This avoids the observer having to rely on memory when comparing two objects under a conventional microscope.
Philip O. Gravelle, a chemist
, developed a comparison microscope for use in the identification of fired bullets and cartridge cases with the support and guidance of forensic ballistics pioneer Calvin Goddard. It was a significant advance in the science of firearms identification in forensic science. The firearm from which a bullet or cartridge case has been fired is identified by the comparison of the unique striae left on the bullet or cartridge case from the worn, machined metal of the barrel
, breach block, extractor
, or firing pin
in the gun
. It was Gravelle who mistrusted his memory. "As long as he could inspect only one bullet at a time with his microscope, and had to keep the picture of it in his memory until he placed the comparison bullet under the microscope, scientific precision could not be attained. He therefore developed the comparison microscope and Goddard made it work." Calvin Goddard perfected the comparison microscope and subsequently popularized its use.Sir Sydney Smith
also appreciated the idea, emphasizing its importance in forensic science and firearms identification. He took the comparison microscope to Scotland
and introduced it to the European scientists for firearms identification and other forensic uses.
components, but at that time neither the software nor the hardware existed to implement the theories. By the 1980s high-capacity computer systems adapted to the requirements of digital imaging
, pattern recognition, image storage and comparison algorithms were available. Cooperation between private industry, law enforcement and forensic subject matter experts lead to the evolution of the Integrated Ballistics Identification System (IBIS)
and electronic
refinements, including fiber optic illumination, video
capabilities, digital imaging, automatic exposure for conventional photography, etc. Despite this evolution, however, the basic tools and techniques have remained unchanged which are to determine whether or not ammunition components were fired by a single firearm
based on unique and reproducible microscopic and class characteristics, or to reach a "no conclusion" result if insufficient marks are present.
Since, ballistic identification has benefited from a long series of structural, scientific and technological advances, law enforcement agencies have established forensic laboratories and researchers have learned much more about how to match bullet
s and cartridge cases to the guns used to fire them, and comparison microscopes have become more sophisticated. By the end of the 1980s, ballistic identification was an established sub-specialty of forensic science.
Visualization tools have also been developed to allows the firearms examiner to verify the degree of similarity between any two tool-marks in question. These are designed to simulate the operation of the comparison microscope but is capable of rendering a 2D view of the 3D surfaces in a manner similar to that of the conventional comparison microscope. It also enables the examiner to translate one tool mark or striae with respect to the other, overlap them, modify illumination conditions, zoom in and out, adjust the point of view of the user, and even provides the ability to create a split image on the screen that includes a hair-line to demarcate one tool-mark on the left of the screen from the other on the right. A unique characteristics of visualization tools include their ability to simulate any material or "palette" which may be useful to the user as well as adjustment of the angle of incidence of the light and the light intensity that can assist in emphasizing certain features in the 3-D images.
With advances in digital imaging technology and data storage capacity, forensic examiners proposed the establishment of a centralized database of images of bullets and cartridge cases that could be compared against a bullet
or cartridge case recovered from a crime scene
. By the mid 1990s, two such systems emerged in the United States
. The first system, developed by the Federal Bureau of Investigation
(FBI), was called "Drugfire
." Drugfire used imaging software to capture, catalog and compare digital images of cartridge cases, bullets were added later. A forensic examiner would capture an image of a recovered bullet or cartridge and compare it with similar images from the database. Drugfire enabled the examiner to see many images of potential matches on one screen, greatly speeding up the process. However, Drugfire did not rank the images by how close a match they were, leaving that determination entirely to the examiner. More than 170 law enforcement agencies nationwide participated in the Drugfire program. The second system, developed by the Bureau of Alcohol, Tobacco and Firearms (ATF), was originally called "Ceasefire." Like Drugfire, Ceasefire used imaging software to capture images of the markings on bullets and included a sophisticated comparison algorithm that automatically identified likely matches. Rather than requiring the examiner to sift through dozens or hundreds of images, the computer presented the examiner with a ranked list of the most likely matches. When the ATF expanded Ceasefire to include cartridge cases, it renamed the program the Integrated Ballistics Identification System (IBIS).
In 1997, the ATF and the FBI agreed to try to combine Drugfire and IBIS to reduce the cost and inefficiency of maintaining both systems. However, technical obstacles prevented the integration of the two systems. After several years a compromise solution emerged. The new system would adopt IBIS's imaging technology and comparison algorithms while relying on the FBI's telecommunications network. Although a few devotees continued to use Drugfire on their own, IBIS became the standard centralized system. The National Integrated Ballistic Information Network (NIBIN) was born.
compared to most other developed countries provided the impetus for the development of the comparison microscope. As with most firearms, the fired ammunition
components may acquire sufficient unique and reproducible microscopic marks to be identifiable as having been fired by a single firearm. Making these comparisons is correctly referred to as firearms identification, or sometimes called as "ballistics".
Historically, and currently, this forensic discipline ultimately requires a microscopic side-by-side comparison of fired bullet
s or cartridge cases, one pair at a time, by a forensic examiner to confirm or eliminate the two items as having been fired by a single firearm. For this purpose, the traditional tool of the firearms examiner has been what is often called the ballistics comparison microscope.
The interior of a gun's barrel is machined to have grooves (called rifling) that force the bullet to rotate as it travels along it. These grooves and their counterpart, called "lands" imprint groove and land impressions on the surface of the bullet. Together with these land and groove impressions, imperfections on the barrel
surface are incidentally transferred to the bullet's surface. Because these imperfections are randomly generated, during manufacture or due to use, they are unique to each barrel. These patterns or imperfections, therefore, amount to a "signature" that each barrel imprints on each of the bullets fired through it. It is this "signature" on the bullets imparted due to the unique imperfections on the barrel that enable the validation and identification of bullets as having originated from a particular gun. Comparison microscope is used to analyze the matching of the microscopic impressions found on the surface of bullets and casings.
When a firearm or a bullet or cartridge case are recovered from a crime scene
, forensic examiners compare the ballistic fingerprint
of the recovered bullet or cartridge case with the ballistic fingerprint of a second bullet or cartridge case test-fired from the recovered firearm. If the ballistic fingerprint on the test-fired bullet or cartridge case matches the ballistic fingerprint on the recovered bullet or cartridge case, investigators know that the recovered bullet or cartridge case was also fired from the recovered gun. A confirmed link between a specific firearm and a bullet or cartridge case recovered from a crime scene constitutes a valuable lead, because investigators may be able to connect the firearm to a person, who may then become either a suspect or a source of information helpful to the investigation.
offered ballistic identification evidence in 1921 to help secure conviction
s of accused murderers and anarchists Nicola Sacco and Bartolomeo Vanzetti. On April 8, 1927, Sacco and Vanzetti were finally sentenced to death in the electric chair
. A worldwide outcry arose and Governor Alvin T. Fuller finally agreed to postpone the executions
and set up a committee to reconsider the case. By this time, firearms examination had improved considerably, and it was now known that an automatic pistol
could be traced by several different methods if both bullet
and casing were recovered from the scene. Automatic pistols could now be traced by unique markings of the rifling on the bullet, by firing pin
indentations on the fired primer, or by unique ejector and extractor
marks on the casing. The committee appointed to review the case used the services of Calvin Goddard
in 1927.
Goddard used Philip Gravelle's newly-invented comparison microscope and helixometer, a hollow, lighted magnifier probe used to inspect gun barrel
s, to make an examination of Sacco's .32 Colt, the bullet that killed Berardelli, and the spent casings recovered from the scene of the crime. In the presence of one of the defense experts, he fired a bullet from Sacco's gun into a wad of cotton and then put the ejected casing on the comparison microscope next to casings found at the scene. Then he looked at them carefully. The first two casings from the robbery did not match Sacco's gun, but the third one did. Even the defense expert agreed that the two cartridges had been fired from the same gun. The second original defense expert also concurred. The committee upheld the convictions.
In October 1961, ballistics tests were run with improved technology using Sacco's Colt automatic. The results confirmed that the bullet that killed the victim, Berardelli in 1920 came from the same .32 Colt Auto taken from the pistol in Sacco's possession. Subsequent investigations in 1983 also supported Goddard's findings.
in which seven gangsters were killed by rival Al Capone
mobsters dressed as Chicago police
officers. It also led to the establishment of the United States' first independent criminological laboratory, which was located at Northwestern University
and headed by Goddard. At this new lab, ballistics
, fingerprinting, blood analysis and trace evidence
were all brought under one roof.
In 1929, using a comparison microscope adapted for the ballistics comparison by his partner, Phillip Gravelle, Goddard used similar techniques to absolve the Chicago Police Department of participation in the St. Valentine's Day Massacre
. The case of Sacco and Vanzetti, which took place in Bridgewater, Massachusetts, is responsible for popularizing the use of the comparison microscope for bullet comparison. Forensic expert Calvin Goddard's conclusions were upheld when the evidence was re-examined in 1961.
Microscope
A microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy...
s connected by an optical bridge, which results in a split view window enabling two separate objects to be viewed simultaneously. This avoids the observer having to rely on memory when comparing two objects under a conventional microscope.
History
In the 1920s forensic ballistics was waiting at its inception. In 1929, using a comparison microscope adapted for the purpose by Calvin Goddard and his partner Phillip Gravelle used similar techniques to absolve the Chicago Police Department of participation in the St. Valentine's Day Massacre.Col. Calvin H. Goddard
Chemist
A chemist is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties such as density and acidity. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms...
, developed a comparison microscope for use in the identification of fired bullets and cartridge cases with the support and guidance of forensic ballistics pioneer Calvin Goddard. It was a significant advance in the science of firearms identification in forensic science. The firearm from which a bullet or cartridge case has been fired is identified by the comparison of the unique striae left on the bullet or cartridge case from the worn, machined metal of the barrel
Gun barrel
A gun barrel is the tube, usually metal, through which a controlled explosion or rapid expansion of gases are released in order to propel a projectile out of the end at a high velocity....
, breach block, extractor
Extractor (firearms)
An extractor is a part in a firearm that serves to remove brass cases of fired ammunition after the ammunition has been fired. When the gun's action cycles, the extractor lifts or removes the spent brass casing from the firing chamber.-Overview:...
, or firing pin
Firing pin
A firing pin or striker is part of the firing mechanism used in a firearm or explosive device e.g. an M14 landmine or bomb fuze. Firing pins may take many forms, though the types used in landmines, bombs, grenade fuzes or other single-use devices generally have a sharpened point...
in the gun
Gun
A gun is a muzzle or breech-loaded projectile-firing weapon. There are various definitions depending on the nation and branch of service. A "gun" may be distinguished from other firearms in being a crew-served weapon such as a howitzer or mortar, as opposed to a small arm like a rifle or pistol,...
. It was Gravelle who mistrusted his memory. "As long as he could inspect only one bullet at a time with his microscope, and had to keep the picture of it in his memory until he placed the comparison bullet under the microscope, scientific precision could not be attained. He therefore developed the comparison microscope and Goddard made it work." Calvin Goddard perfected the comparison microscope and subsequently popularized its use.Sir Sydney Smith
Sydney Smith (forensic expert)
Sir Sydney Alfred Smith CBE , was a renowned forensic scientist and pathologist. From 1928 to 1953, Smith was Regius Professor of Forensic Medicine at the University of Edinburgh, a well-known forensic department of that time...
also appreciated the idea, emphasizing its importance in forensic science and firearms identification. He took the comparison microscope to Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
and introduced it to the European scientists for firearms identification and other forensic uses.
The present
During the 1960s there were proposals to computerize the process of microscopic comparisons of fired ammunitionAmmunition
Ammunition is a generic term derived from the French language la munition which embraced all material used for war , but which in time came to refer specifically to gunpowder and artillery. The collective term for all types of ammunition is munitions...
components, but at that time neither the software nor the hardware existed to implement the theories. By the 1980s high-capacity computer systems adapted to the requirements of digital imaging
Digital imaging
Digital imaging or digital image acquisition is the creation of digital images, typically from a physical scene. The term is often assumed to imply or include the processing, compression, storage, printing, and display of such images...
, pattern recognition, image storage and comparison algorithms were available. Cooperation between private industry, law enforcement and forensic subject matter experts lead to the evolution of the Integrated Ballistics Identification System (IBIS)
Modern comparison microscope
The modern instrument has many optical, mechanicalMachine
A machine manages power to accomplish a task, examples include, a mechanical system, a computing system, an electronic system, and a molecular machine. In common usage, the meaning is that of a device having parts that perform or assist in performing any type of work...
and electronic
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
refinements, including fiber optic illumination, video
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
capabilities, digital imaging, automatic exposure for conventional photography, etc. Despite this evolution, however, the basic tools and techniques have remained unchanged which are to determine whether or not ammunition components were fired by a single firearm
Firearm
A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...
based on unique and reproducible microscopic and class characteristics, or to reach a "no conclusion" result if insufficient marks are present.
Since, ballistic identification has benefited from a long series of structural, scientific and technological advances, law enforcement agencies have established forensic laboratories and researchers have learned much more about how to match bullet
Bullet
A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...
s and cartridge cases to the guns used to fire them, and comparison microscopes have become more sophisticated. By the end of the 1980s, ballistic identification was an established sub-specialty of forensic science.
Visualization tools have also been developed to allows the firearms examiner to verify the degree of similarity between any two tool-marks in question. These are designed to simulate the operation of the comparison microscope but is capable of rendering a 2D view of the 3D surfaces in a manner similar to that of the conventional comparison microscope. It also enables the examiner to translate one tool mark or striae with respect to the other, overlap them, modify illumination conditions, zoom in and out, adjust the point of view of the user, and even provides the ability to create a split image on the screen that includes a hair-line to demarcate one tool-mark on the left of the screen from the other on the right. A unique characteristics of visualization tools include their ability to simulate any material or "palette" which may be useful to the user as well as adjustment of the angle of incidence of the light and the light intensity that can assist in emphasizing certain features in the 3-D images.
With advances in digital imaging technology and data storage capacity, forensic examiners proposed the establishment of a centralized database of images of bullets and cartridge cases that could be compared against a bullet
Bullet
A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...
or cartridge case recovered from a crime scene
Crime scene
A crime scene is a location where an illegal act took place, and comprises the area from which most of the physical evidence is retrieved by trained law enforcement personnel, crime scene investigators or in rare circumstances, forensic scientists....
. By the mid 1990s, two such systems emerged in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. The first system, developed by the Federal Bureau of Investigation
Federal Bureau of Investigation
The Federal Bureau of Investigation is an agency of the United States Department of Justice that serves as both a federal criminal investigative body and an internal intelligence agency . The FBI has investigative jurisdiction over violations of more than 200 categories of federal crime...
(FBI), was called "Drugfire
Drugfire
DRUGFIRE is a multimedia database imaging system that automates the comparison of images of bullet cartridge cases, shell casings and bullets that was developed by MSI . It is a multimedia database imaging system that allows examiners from across the country to compare and link evidence obtained...
." Drugfire used imaging software to capture, catalog and compare digital images of cartridge cases, bullets were added later. A forensic examiner would capture an image of a recovered bullet or cartridge and compare it with similar images from the database. Drugfire enabled the examiner to see many images of potential matches on one screen, greatly speeding up the process. However, Drugfire did not rank the images by how close a match they were, leaving that determination entirely to the examiner. More than 170 law enforcement agencies nationwide participated in the Drugfire program. The second system, developed by the Bureau of Alcohol, Tobacco and Firearms (ATF), was originally called "Ceasefire." Like Drugfire, Ceasefire used imaging software to capture images of the markings on bullets and included a sophisticated comparison algorithm that automatically identified likely matches. Rather than requiring the examiner to sift through dozens or hundreds of images, the computer presented the examiner with a ranked list of the most likely matches. When the ATF expanded Ceasefire to include cartridge cases, it renamed the program the Integrated Ballistics Identification System (IBIS).
In 1997, the ATF and the FBI agreed to try to combine Drugfire and IBIS to reduce the cost and inefficiency of maintaining both systems. However, technical obstacles prevented the integration of the two systems. After several years a compromise solution emerged. The new system would adopt IBIS's imaging technology and comparison algorithms while relying on the FBI's telecommunications network. Although a few devotees continued to use Drugfire on their own, IBIS became the standard centralized system. The National Integrated Ballistic Information Network (NIBIN) was born.
Forensic ballistics
The prevalence of hand-gun related crime in the United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
compared to most other developed countries provided the impetus for the development of the comparison microscope. As with most firearms, the fired ammunition
Ammunition
Ammunition is a generic term derived from the French language la munition which embraced all material used for war , but which in time came to refer specifically to gunpowder and artillery. The collective term for all types of ammunition is munitions...
components may acquire sufficient unique and reproducible microscopic marks to be identifiable as having been fired by a single firearm. Making these comparisons is correctly referred to as firearms identification, or sometimes called as "ballistics".
Historically, and currently, this forensic discipline ultimately requires a microscopic side-by-side comparison of fired bullet
Bullet
A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...
s or cartridge cases, one pair at a time, by a forensic examiner to confirm or eliminate the two items as having been fired by a single firearm. For this purpose, the traditional tool of the firearms examiner has been what is often called the ballistics comparison microscope.
The interior of a gun's barrel is machined to have grooves (called rifling) that force the bullet to rotate as it travels along it. These grooves and their counterpart, called "lands" imprint groove and land impressions on the surface of the bullet. Together with these land and groove impressions, imperfections on the barrel
Gun barrel
A gun barrel is the tube, usually metal, through which a controlled explosion or rapid expansion of gases are released in order to propel a projectile out of the end at a high velocity....
surface are incidentally transferred to the bullet's surface. Because these imperfections are randomly generated, during manufacture or due to use, they are unique to each barrel. These patterns or imperfections, therefore, amount to a "signature" that each barrel imprints on each of the bullets fired through it. It is this "signature" on the bullets imparted due to the unique imperfections on the barrel that enable the validation and identification of bullets as having originated from a particular gun. Comparison microscope is used to analyze the matching of the microscopic impressions found on the surface of bullets and casings.
When a firearm or a bullet or cartridge case are recovered from a crime scene
Crime scene
A crime scene is a location where an illegal act took place, and comprises the area from which most of the physical evidence is retrieved by trained law enforcement personnel, crime scene investigators or in rare circumstances, forensic scientists....
, forensic examiners compare the ballistic fingerprint
Ballistic fingerprinting
Ballistic fingerprinting refers to a set of forensic techniques that rely on marks that firearms leave on bullets to match a bullet to the gun it was fired with...
of the recovered bullet or cartridge case with the ballistic fingerprint of a second bullet or cartridge case test-fired from the recovered firearm. If the ballistic fingerprint on the test-fired bullet or cartridge case matches the ballistic fingerprint on the recovered bullet or cartridge case, investigators know that the recovered bullet or cartridge case was also fired from the recovered gun. A confirmed link between a specific firearm and a bullet or cartridge case recovered from a crime scene constitutes a valuable lead, because investigators may be able to connect the firearm to a person, who may then become either a suspect or a source of information helpful to the investigation.
Sacco and Vanzetti case
Forensic innovator Calvin GoddardCalvin Goddard (Ballistics)
Colonel Calvin Hooker Goddard was a forensic scientist, army officer, academic, researcher and a pioneer in forensic ballistics. He was born in Baltimore, Maryland...
offered ballistic identification evidence in 1921 to help secure conviction
Conviction
In law, a conviction is the verdict that results when a court of law finds a defendant guilty of a crime.The opposite of a conviction is an acquittal . In Scotland and in the Netherlands, there can also be a verdict of "not proven", which counts as an acquittal...
s of accused murderers and anarchists Nicola Sacco and Bartolomeo Vanzetti. On April 8, 1927, Sacco and Vanzetti were finally sentenced to death in the electric chair
Electric chair
Execution by electrocution, usually performed using an electric chair, is an execution method originating in the United States in which the condemned person is strapped to a specially built wooden chair and electrocuted through electrodes placed on the body...
. A worldwide outcry arose and Governor Alvin T. Fuller finally agreed to postpone the executions
Capital punishment
Capital punishment, the death penalty, or execution is the sentence of death upon a person by the state as a punishment for an offence. Crimes that can result in a death penalty are known as capital crimes or capital offences. The term capital originates from the Latin capitalis, literally...
and set up a committee to reconsider the case. By this time, firearms examination had improved considerably, and it was now known that an automatic pistol
Automatic pistol
Automatic pistol may refer to:* Machine pistol, a handgun-style, magazine-fed and self-loading firearm, capable of fully automatic or burst fire, and chambered for pistol cartridges...
could be traced by several different methods if both bullet
Bullet
A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...
and casing were recovered from the scene. Automatic pistols could now be traced by unique markings of the rifling on the bullet, by firing pin
Firing pin
A firing pin or striker is part of the firing mechanism used in a firearm or explosive device e.g. an M14 landmine or bomb fuze. Firing pins may take many forms, though the types used in landmines, bombs, grenade fuzes or other single-use devices generally have a sharpened point...
indentations on the fired primer, or by unique ejector and extractor
Extractor (firearms)
An extractor is a part in a firearm that serves to remove brass cases of fired ammunition after the ammunition has been fired. When the gun's action cycles, the extractor lifts or removes the spent brass casing from the firing chamber.-Overview:...
marks on the casing. The committee appointed to review the case used the services of Calvin Goddard
Calvin Goddard (Ballistics)
Colonel Calvin Hooker Goddard was a forensic scientist, army officer, academic, researcher and a pioneer in forensic ballistics. He was born in Baltimore, Maryland...
in 1927.
Goddard used Philip Gravelle's newly-invented comparison microscope and helixometer, a hollow, lighted magnifier probe used to inspect gun barrel
Gun barrel
A gun barrel is the tube, usually metal, through which a controlled explosion or rapid expansion of gases are released in order to propel a projectile out of the end at a high velocity....
s, to make an examination of Sacco's .32 Colt, the bullet that killed Berardelli, and the spent casings recovered from the scene of the crime. In the presence of one of the defense experts, he fired a bullet from Sacco's gun into a wad of cotton and then put the ejected casing on the comparison microscope next to casings found at the scene. Then he looked at them carefully. The first two casings from the robbery did not match Sacco's gun, but the third one did. Even the defense expert agreed that the two cartridges had been fired from the same gun. The second original defense expert also concurred. The committee upheld the convictions.
In October 1961, ballistics tests were run with improved technology using Sacco's Colt automatic. The results confirmed that the bullet that killed the victim, Berardelli in 1920 came from the same .32 Colt Auto taken from the pistol in Sacco's possession. Subsequent investigations in 1983 also supported Goddard's findings.
St. Valentine's Day massacre
Colonel Goddard was the key forensic expert in solving the 1929 St. Valentine's Day MassacreSt. Valentine's Day massacre
The Saint Valentine's Day massacre is the name given to the 1929 murder of 7 mob associates as part of a prohibition era conflict between two powerful criminal gangs in Chicago: the South Side Italian gang led by Al Capone and the North Side Irish gang led by Bugs Moran. Former members of the...
in which seven gangsters were killed by rival Al Capone
Al Capone
Alphonse Gabriel "Al" Capone was an American gangster who led a Prohibition-era crime syndicate. The Chicago Outfit, which subsequently became known as the "Capones", was dedicated to smuggling and bootlegging liquor, and other illegal activities such as prostitution, in Chicago from the early...
mobsters dressed as Chicago police
Chicago Police Department
The Chicago Police Department, also known as the CPD, is the principal law enforcement agency of Chicago, Illinois, in the United States, under the jurisdiction of the Mayor of Chicago. It is the largest police department in the Midwest and the second largest local law enforcement agency in the...
officers. It also led to the establishment of the United States' first independent criminological laboratory, which was located at Northwestern University
Northwestern University
Northwestern University is a private research university in Evanston and Chicago, Illinois, USA. Northwestern has eleven undergraduate, graduate, and professional schools offering 124 undergraduate degrees and 145 graduate and professional degrees....
and headed by Goddard. At this new lab, ballistics
Ballistics
Ballistics is the science of mechanics that deals with the flight, behavior, and effects of projectiles, especially bullets, gravity bombs, rockets, or the like; the science or art of designing and accelerating projectiles so as to achieve a desired performance.A ballistic body is a body which is...
, fingerprinting, blood analysis and trace evidence
Trace evidence
Trace evidence is evidence that occurs when different objects contact one another. Such materials are often transferred by heat induced by contact friction....
were all brought under one roof.
In 1929, using a comparison microscope adapted for the ballistics comparison by his partner, Phillip Gravelle, Goddard used similar techniques to absolve the Chicago Police Department of participation in the St. Valentine's Day Massacre
St. Valentine's Day massacre
The Saint Valentine's Day massacre is the name given to the 1929 murder of 7 mob associates as part of a prohibition era conflict between two powerful criminal gangs in Chicago: the South Side Italian gang led by Al Capone and the North Side Irish gang led by Bugs Moran. Former members of the...
. The case of Sacco and Vanzetti, which took place in Bridgewater, Massachusetts, is responsible for popularizing the use of the comparison microscope for bullet comparison. Forensic expert Calvin Goddard's conclusions were upheld when the evidence was re-examined in 1961.
External links
See also
- Association of Firearm and Tool Mark ExaminersAssociation of Firearm and Tool Mark ExaminersThe Association of Firearm and Tool Mark Examiners is an international non-profit organization dedicated to the advancement of firearm and tool mark identification, which is one of the forensic sciences.- Organizational history :...
- RiflingRiflingRifling is the process of making helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis...