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Comparison Microscope
A comparison microscope is a device used to analyze side-by-side specimens. It consists of two microscopes 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 One of the first prototypes of a comparison microscope was developed in 1913 in Germany. In 1929, using a comparison microscope adapted for forensic ballistics, Calvin Goddard and his partner Philip Gravelle were able to absolve the Chicago Police Department of participation in the St. Valentine's Day Massacre. Col. Calvin H. Goddard Philip O. Gravelle, a chemist, developed a comparison microscope for use in the identification of fired bullets and Casing (ammunition), 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Firearm
A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and operated by an individual. The term is legally defined further in different countries (see legal definitions). The first firearms originated in 10th-century China, when bamboo tubes containing gunpowder and pellet projectiles were mounted on spears to make the portable fire lance, operable by a single person, which was later used effectively as a shock weapon in the siege of De'an in 1132. In the 13th century, fire lance barrels were replaced with metal tubes and transformed into the metal-barreled hand cannon. The technology gradually spread throughout Eurasia during the 14th century. Older firearms typically used black powder as a propellant, but modern firearms use smokeless powder or other explosive propellants. Most modern firearms (with the notable exception of smoothbore shotguns) have rifled barrels to impart spin to the projectile for improved flight stabili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Semi-automatic Pistol
A semi-automatic pistol (also called a self-loading pistol, autopistol, or autoloading pistol) is a repeating firearm, repeating handgun that automatically ejects and loads cartridge (firearms), cartridges in its chamber (firearms), chamber after every shot fired, but only one round of ammunition is fired each time the Trigger (firearms), trigger is pulled. The pistol's fire control group disconnects the trigger mechanism from the firing pin/striker until the trigger has been released and reset manually, unlike the self-cycled firing mechanism in machine pistol, fully automatic pistols. A semi-automatic pistol recycles part of the energy released by the propellant combustion to move its bolt (firearm), bolt, which is usually housed inside the pistol slide, slide. After a round of ammunition is fired, the spent cartridge casing is extracted and ejected as the slide/bolt moves rearwards under recoil, the hammer (firearms), hammer/striker is cocked by the slide/bolt movement, and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Capital Punishment
Capital punishment, also known as the death penalty and formerly called judicial homicide, is the state-sanctioned killing of a person as punishment for actual or supposed misconduct. The sentence (law), sentence ordering that an offender be punished in such a manner is called a death sentence, and the act of carrying out the sentence is an execution. A prisoner who has been sentenced to death and awaits execution is ''condemned'' and is commonly referred to as being "on death row". Etymologically, the term ''capital'' (, derived via the Latin ' from ', "head") refers to execution by Decapitation, beheading, but executions are carried out by List of methods of capital punishment, many methods, including hanging, Execution by shooting, shooting, lethal injection, stoning, Electric chair, electrocution, and Gas chamber, gassing. Crimes that are punishable by death are known as ''capital crimes'', ''capital offences'', or ''capital felonies'', and vary depending on the jurisdic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Electric Chair
The electric chair is a specialized device used for capital punishment through electrocution. The condemned is strapped to a custom wooden chair and electrocuted via electrodes attached to the head and leg. Alfred P. Southwick, a Buffalo, New York dentist, conceived this execution method in 1881. It was developed over the next decade as a more humane alternative to conventional executions, particularly hanging. First used in 1890, the electric chair became a symbol of capital punishment in the United States. The electric chair was also used extensively in the Philippines. It was initially thought to cause death through cerebral damage, but it was scientifically established in 1899 that death primarily results from ventricular fibrillation and cardiac arrest. Despite its historical significance in American capital punishment, electric chair use has declined with the adoption of lethal injection which was perceived as more humane. While some states retain electrocution as a legal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Bartolomeo Vanzetti
Nicola Sacco (; April 22, 1891 – August 23, 1927) and Bartolomeo Vanzetti (; June 11, 1888 – August 23, 1927) were Italian immigrants and anarchists who were controversially convicted of murdering Alessandro Berardelli and Frederick Parmenter, a guard and a paymaster, during the April 15, 1920, armed robbery of the Slater and Morrill Shoe Company in Braintree, Massachusetts, United States. Seven years later, they were executed in the electric chair at Charlestown State Prison. After a few hours' deliberation on July 14, 1921, the jury convicted Sacco and Vanzetti of first-degree murder and they were sentenced to death by the trial judge. Anti-Italianism, anti-immigrant, and anti-anarchist bias were suspected as having heavily influenced the verdict. A series of appeals followed, funded largely by the private Sacco and Vanzetti Defense Committee. The appeals were based on recanted testimony, conflicting ballistics evidence, a prejudicial pretrial statement by the jury ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Nicola Sacco
Nicola Sacco (; April 22, 1891 – August 23, 1927) and Bartolomeo Vanzetti (; June 11, 1888 – August 23, 1927) were Italian immigrants and anarchists who were controversially convicted of murdering Alessandro Berardelli and Frederick Parmenter, a guard and a paymaster, during the April 15, 1920, armed robbery of the Slater and Morrill Shoe Company in Braintree, Massachusetts, United States. Seven years later, they were executed in the electric chair at Charlestown State Prison. After a few hours' deliberation on July 14, 1921, the jury convicted Sacco and Vanzetti of first-degree murder and they were sentenced to death by the trial judge. Anti-Italianism, anti-immigrant, and anti-anarchist bias were suspected as having heavily influenced the verdict. A series of appeals followed, funded largely by the private Sacco and Vanzetti Defense Committee. The appeals were based on recanted testimony, conflicting ballistics evidence, a prejudicial pretrial statement by the jury fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Conviction
In law, a conviction is the determination by a court of law that a defendant is Guilty (law), guilty of a crime. A conviction may follow a guilty plea that is accepted by the court, a jury trial in which a verdict of guilty is delivered, or a trial by judge in which the defendant is found guilty. The opposite of a conviction is an acquittal (that is, "not guilty"). In Scotland, there can also be a verdict of "not proven", which is considered an acquittal. Sometimes, despite a defendant being found guilty, the court may order that the defendant not be convicted. This is known as a Discharge (sentence), discharge and is used in countries including England, Wales, Canada, Australia, and New Zealand. In any criminal justice system, innocent people are sometimes convicted. Appeal mechanisms and post conviction relief procedures may help to address this issue to some extent. An error leading to the conviction of an innocent person is known as a miscarriage of justice. In some judici ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Calvin Hooker Goddard
Calvin Hooker Goddard (30 October 1891 – 22 February 1955) was a forensic scientist, army officer, academic, researcher and a pioneer in forensic ballistics. He examined the bullet casings in the 1929 St. Valentine's Day Massacre and showed that the guns used were not police issued weapons, leading the investigators to conclude it was a mob hit. Biography Goddard was born in Baltimore, Maryland. After graduating from the Boys' Latin School of Maryland in 1907, he graduated with a Bachelor of Arts degree in 1911 from the Johns Hopkins University, later earning a medical degree and graduating 1915. He joined the United States Army and became a Colonel. He was also a professor of police science at Northwestern University and the military editor of the Encyclopædia Britannica. He was also the editor of the American Journal of Police Science, America's first scientific police journal. Colonel Goddard commanded the US Army Crime Laboratory in Japan for a number of years after World ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Ballistic Fingerprinting
Forensic firearm examination is the forensic process of examining the characteristics of firearms or bullets left behind at a crime scene. Specialists in this field try to link bullets to weapons and weapons to individuals. They can raise and record obliterated serial numbers in an attempt to find the registered owner of a weapon and look for fingerprints on a weapon and cartridges. By examining unique striations impressed into a bullet from the barrel of a gun, expended ammunition can be linked back to a specific weapon. These striations are due to the rifling inside the barrels of firearms. Rifling spins the bullet when it is fired out of the barrel to improve precision. Although bullet striations are individualized unique evidence, microscopic striations in the barrel of the weapon are subject to change slightly, after each round that is fired. For this reason, forensic ballistics examiners may not fire more than five shots from a weapon found at a scene. Known exemplars take ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Crime Scene
A crime scene is any location that may be associated with a committed crime. Crime scenes contain physical evidence that is pertinent to a criminal investigation. This evidence is collected by crime scene investigators (CSI) and law enforcement. The location of a crime scene can be the place where the crime took place or can be any area that contains evidence from the crime itself. Scenes are not only limited to a location, but can be any person, place, or object associated with the criminal behaviours that occurred. Immediately after the discovery of a crime scene, measures must be taken to secure and protect the scene from contamination. To maintain the integrity of the scene, law enforcement must take action to block off the surrounding area as well as keep track of who comes in and goes out. By taking these precautions, officers can ensure that evidence that is collected can be used in court. Evidence that has become contaminated, tampered with, or mistreated can pollute th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Rifling
Rifling is the term for helical grooves machined into the internal surface of a firearms's barrel for imparting a spin to a projectile to improve its aerodynamic stability and accuracy. It is also the term (as a verb) for creating such grooves. The opposite of rifling is smoothbore. Rifling is measured in ''twist rate'', the distance the rifling takes to complete one full revolution, expressed as a ratio with 1 as its base (e.g., 1:). A shorter distance/lower ratio indicates a faster twist, generating a higher spin rate (and greater projectile stability). The combination of length, weight, and shape of a projectile determines the twist rate needed to gyroscopically stabilize it: barrels intended for short, large-diameter projectiles such as spherical lead balls require a very low twist rate, such as 1 turn in 48 inches (122 cm). Barrels intended for long, small-diameter projectiles, such as the ultra-low-drag 80-grain 0.223 inch bullets (5.2 g, 5.56&nb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |