What are the characteristics of bullets?

These characteristics are based upon “striae” left on the bullet as it passes through the barrel. Class refers to the type of caliber and rifling. Rifling pattern may turn to the right or left, with a given rate of twist. The number and depth of grooves can vary also.

How Class evidence may be useful?

Class evidence may be useful when there are different types of evidence or there is a lot of it. It is collected from the victim or suspects for comparison with the unknown or questioned crime scene evidence. In a laboratory context, a control is often a sample used to test a method, and a standard is a known sample.

What is the greatest weakness of class physical evidence and what is the main reason for this weakness?

What is the main reason for this weakness? The greatest weakness of class physical evidence is that it cannot relate physical evidence to a common origin with a high degree of certainty. Evidence possessing class characteristics can be associated only with a group and never with a single source.

What is class characteristic evidence?

∎ Class: a group of objects or persons with. characteristic physical evidence common to it. ∎ Examples include soil and hair. ∎ Individual characteristics can be identified as. having originated with a particular person or.

What is a class characteristic?

All evidence bears class characteristics. Individual characteristics may or may not be present. Evidence that possesses class characteristics may be referred to as class evidence. Similarly, evidence that possesses individual characteristics may be referred to as individual evidence.

What are individual characteristics of firearms?

Individual characteristics are marks unique to that particular firearm barrel. In a barrel, the individual characteristics are produced by the random imperfections and irregularities of the tool or tools used to produce the lands and grooves, and by use, corrosion, or damage.

How long do impressions need before they can be analyzed?

3.09 Physical Evidence Exam Help Question 1 (Worth 1 points) How long do casts of impressions need to sit before they can be analyzed? 5 minutes 1 hour 5 hours 24 hours Points earned on this question: 1 Question 2 (Worth 1 points) Class characteristics are those associated with what?

How is hair a class evidence?

Explain how and when hair is considered as class evidence, and when it’s considered individual evidence. Hair is considered class evidence when the follicle is not attached because the follicle is the part that contains DNA. When the follicle is attached, it is considered individual evidence.

What is the definition of physical evidence?

Physical evidence (also called real evidence or material evidence) is any material object that plays some role in the matter that gave rise to the litigation, introduced as evidence in a judicial proceeding (such as a trial) to prove a fact in issue based on the object’s physical characteristics.

What is the definition of biological evidence?

Biological evidence refers to samples of biological material—such as hair, tissue, bones, teeth, blood, semen, or other bodily fluids—or to evidence items containing biological material (DNA Initiative 2012).

What is the definition of direct evidence?

Direct evidence supports the truth of an assertion (in criminal law, an assertion of guilt or of innocence) directly, i.e., without an intervening inference. For example: a witness who testifies that he saw the defendant shoot the victim gives direct evidence.

What is the Locard’s exchange principle?

In forensic science, Locard’s exchange principle holds that the perpetrator of a crime will bring something into the crime scene and leave with something from it, and that both can be used as forensic evidence.

What is the difference between individual and class evidence?

Class characteristics are not unique to a particular object but place the particular bit of evidence into a group of objects. Individual characteristics narrow down the evidence to a single, individual source. The type of handgun with which a victim is shot is a class characteristic.

What are chamber marks?

Striated action marks can be produced on cartridge cases by contact with a number of different areas within the firearm. Some of the more common striated action marks include chamber marks; shear marks, firing pin drag marks, extractor marks, and ejector marks. Most chamber marks occur after the cartridge is fired.

What is the trace evidence?

The Trace Evidence Unit (TEU) identifies and compares specific types of trace materials that could be transferred during the commission of a violent crime. These trace materials include human hair, animal hair, textile fibers and fabric, rope, soil, glass, and building materials.

What is the area between the grooves of a gun barrel called?

Also called a long gun. Rifling: The spiral grooves cut or swaged inside a gun barrel that gives the bullet a spinning motion. The metal between the grooves is called a “land”.

How do you match a bullet to a gun?

Striations on a fired bullet. If you are able to fire another bullet from the same gun, an investigator can match the grooves under a special microscope which displays both bullets side by side, comparing the strata. Since there are several processes involved in rifling a barrel, each barrel is unique.

What is the difference between a penetrating gunshot wound and a perforating gunshot wound?

Gunshot wounds can be either penetrating or perforating. In a penetrating wound, the bullet enters an object and remains inside, while in a perforating wound, the bullet passes completely through the object. An exit wound differs greatly from an entrance wound.

Who made the comparison 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.

What is the definition of fracture match?

Fracture Match. The matching of broken or torn objects may be similar to putting together the pieces of a jigsaw puzzle. The edges and surface markings are used to align the items in question. This may substantiate that two or more pieces of an object may have a common origin or at one time were one complete unit.

What is the chain of custody?

Chain of custody (CoC), in legal contexts, refers to the chronological documentation or paper trail that records the sequence of custody, control, transfer, analysis, and disposition of physical or electronic evidence.

When was the rifled barrel invented?

Barrel rifling was invented in Augsburg, Germany in 1498. In 1520 August Kotter, an armourer of Nuremberg, Germany improved upon this work. Though true rifling dates from the mid-16th century, it did not become commonplace until the nineteenth century.