|
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 Phillip 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 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. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Firearm
A firearm is any type of gun designed to be readily carried and used 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 propellants. Most modern firearms (with the notable exception of smoothbore shotguns) have rifled barrels to impart spin to the projectile for improved flight stability. Modern firearms can be described by their caliber ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semi-automatic Pistol
A semi-automatic pistol is a type of repeating single-chamber handgun ( pistol) that automatically cycles its action to insert the subsequent cartridge into the chamber (self-loading), but requires manual actuation of the trigger to actually discharge the following shot. As a result, only one round of ammunition is fired each time the trigger is pulled, as the pistol's fire control group disconnects the trigger mechanism from the firing pin/ striker until the trigger has been released and reset. Additional terms sometimes used as synonyms for a semi-automatic pistol are self-loading pistol, autopistol, autoloading pistol, and automatic pistol (E.G.: Automatic Colt Pistol). A semi-automatic pistol recycles part of the energy released by the propellant combustion to move its bolt, which is usually housed inside the 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/s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capital Punishment
Capital punishment, also known as the death penalty, is the state-sanctioned practice of deliberately killing a person as a punishment for an actual or supposed crime, usually following an authorized, rule-governed process to conclude that the person is responsible for violating norms that warrant said punishment. The sentence ordering that an offender is to be punished in such a manner is known as a death sentence, and the act of carrying out the sentence is known as 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". Crimes that are punishable by death are known as ''capital crimes'', ''capital offences'', or ''capital felonies'', and vary depending on the jurisdiction, but commonly include serious crimes against the person, such as murder, mass murder, aggravated cases of rape (often including child sexual abuse), terrorism, aircraft hijacking, war crimes, crimes against h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Chair
An electric chair is a device used to execute an individual by electrocution. When used, the condemned person is strapped to a specially built wooden chair and electrocuted through electrodes fastened on the head and leg. This execution method, conceived in 1881 by a Buffalo, New York dentist named Alfred P. Southwick, was developed throughout the 1880s as a supposed humane alternative to hanging, and first used in 1890. The electric chair has been used in the United States and, for several decades, in the Philippines. While death was originally theorized to result from damage to the brain, it was shown in 1899 that it primarily results from ventricular fibrillation and eventual cardiac arrest. Although the electric chair has long been a symbol of the death penalty in the United States, its use is in decline due to the rise of lethal injection, which is widely believed to be a more humane method of execution. While some states still maintain electrocution as a legal method of ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bartolomeo Vanzetti
Nicola Sacco (; April 22, 1891 – August 23, 1927) and Bartolomeo Vanzetti (; June 11, 1888 – August 23, 1927) were Italian immigrant anarchists who were controversially accused of murdering Alessandro Berardelli and Frederick Parmenter, a guard and paymaster respectively, 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] |
Nicola Sacco
Nicola Sacco (; April 22, 1891 – August 23, 1927) and Bartolomeo Vanzetti (; June 11, 1888 – August 23, 1927) were Italian immigrant anarchists who were controversially accused of murdering Alessandro Berardelli and Frederick Parmenter, a guard and paymaster respectively, 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] |
Conviction
In law, a conviction is the verdict reached by a court of law finding a defendant guilty of a crime. 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 and is used in countries such as England, Wales, Canada, Australia, and New Zealand. The criminal justice system is not perfect and there are instances in which guilty defendants are acquitted and innocent people are 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. After a defendant is convicted, the court determines the appropriate sentence as a punishment. In addition to the sentence, a conviction can also have other consequ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 and then earned a medical degree and graduated in 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 Wor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 taken ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. After a crime scene has been discovered, 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 the scene an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rifling
In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun's barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the projectile longitudinally by conservation of angular momentum, improving its aerodynamic stability and accuracy over smoothbore designs. Rifling is characterized by its twist rate, which indicates the distance the rifling takes to complete one full revolution, such as "1 turn in 10 inches" (1:10 inches), "1 turn in 254 mm" ("1:254 mm" or "1:25.4 cm)", or the like. Normally, an experienced shooter can infer the units of measurement from the numbers alone. A shorter distance indicates a faster twist, meaning that for a given velocity the projectile will rotate at a higher spin rate. The combination of length, weight, and shape of a projectile determines the twist rate needed to gyroscopically stabilize it – barrel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
