The type of firearm used to shoot a victim is a class characteristic. For instance, if the bullet was fired from a.38 caliber pistol, each Following that, DNA (an individual characteristic) from the suspect and DNA from the blood evidence are examined to establish whether they match definitely. If so, the case can be submitted to the jury with instructions on how they can use the information to determine guilt or innocence.
Individual pieces of evidence may also be relevant to the case. For example, if the gun used to shoot the victim is never found, then testimony about the size of the gunsmile in relation to the blood spatter on the wall could help the jury decide where to place the mark when making their judgment as to how the crime occurred. The size of the gun relative to the blood spatter would be an important factor for the jury to consider.
Bullet casings are remnants of ammunition cases used by shooters who have been practicing. They make up approximately 95% of all firearms evidence. Bloodstain patterns on bullets or bullet casings can give clues about what happened during the crime. A forensic anthropologist might be asked to analyze the pattern to see if there is any correlation between the position of the body when it was shot and the location of the bloodstains on the bullet or casing.
The properties of firearms evidence are comparable to those of fingerprints. They are unique and a valuable source of forensic evidence. Many violent crimes nowadays are committed with weapons, yet the crime scene and firearms evidence can give clues to solve the mystery and bring the guilty to justice.
Firearms evidence includes physical traces of a firearm on or near the victim, suspects, or crime scenes. These traces can be very useful in determining who had access to the weapon and when. They can also reveal what type of ammunition was used with the gun. Finally, firearms evidence includes the actual weapon itself. When a firearm is recovered at the scene of the crime, it is usually in working order. However, it may not fire any bullets if it has been altered or modified by someone other than the manufacturer. In this case, the police may be able to match the characteristics of the weapon (such as the caliber) with information from other sources.
Firearms evidence is important in homicide investigations because they represent one of the only ways to identify the perpetrator. Also, guns can be used during robberies to threaten victims or force them into doing what the robber wants. Finally, guns are often stolen and later used in other crimes. Knowing that a firearm was involved in the crime can help investigators locate it.
The hypothesis behind firearm identification is that tiny striations and imprints left on bullets and cartridge casings are unique and reproducible, and may thus be used to identify a gun, much like "ballistic fingerprints." A fired bullet with rifling imprints from a gun's barrel (left). The same bullet after being shot again with no other guns involved (right). The ballistic expert can tell which version of the bullet was fired from which weapon by looking at these impressions.
In practice, this method of identification is very difficult. Each time a bullet is fired, it leaves an impression in the bullet mold or in some other surface it comes in contact with. These impressions will usually differ if the bullet is fired from different weapons. Also, since only one side of most bullets is rifled, they will not leave any marks when they are fired through firearms' barrels.
It is possible with special equipment to read microscopic markings on bullets that some manufacturers add for identification purposes. However, since all guns produce bullets with some degree of variation in their dimensions and surface textures, perfect matches between bullets and guns are rare.
For example, two bullets with identical designs and production processes may have different staining patterns when stained with certain dyes. Or, they may exhibit different micro-patterns when examined under a microscope.
The size of the bullet (diameter), the number of lands and grooves, the twist of the rifling (left or right), and the widths of the land and groove imprints are all class features seen on a fired bullet. These characteristics help forensic scientists match bullets to their guns.
Each Class B firearm is allowed one non-typical shot per month. If a person takes more than one non-typical shot with a firearm in one month, it becomes a Class A firearm for purposes of this rule. Non-typical shots include those taken during target practice, hunting tests, matches, etc. A firearm is also considered a Class A weapon if it has been reported as lost or stolen.
A firearm is defined as a gun that uses pressure from an explosion to fire the projectile. This includes pistols, revolvers, rifles, shotguns, grenade launchers, and air guns. Certain items such as BB guns, sling bullets, and paintballs do not count as firearms because they use energy stored in some type of reservoir instead of an explosive charge. However, these items can still cause serious injury or death if they are used improperly or accidentally discharged.
Class A firearms must be registered with the local police department if they are being kept at home. If a firearm is found to be illegally possessed or used, its owner may be subject to criminal charges.