Science research » Forensic Science

Discovering Physical Forensic Science

admin — Tue, 22 Jun 2010 10:12:13 +0000

You have watched it on the TV show CSI, and noted how CSI technicians collect evidence from a crime scene in order determine the who, what, when, where, why, and how involved in a crime.

In a science called physical forensic science, there are four aspects involved. In this article, I will define the four aspects of physical forensic science so that the next time you watch CSI, you will have a better understanding of what police scientists talk about.

What is physical forensic science?

Searching for trace evidence, identifying the type of firearm used by studying its projectile, studying the handwriting of a signature on a document, and analyzing the ridges of fingerprints under a microscope all are a part of the physical aspect of forensic science.

Trace evidence

Trace evidence refers to any small item of evidence such as glass, paint, fiber, hair, or soil. Such evidence puts the suspect at the crime scene or in direct contact with the victim. Matching glass shards found on the victim of a hit-and-run vehicle accident to glass shards taken from the broken turn signal lamp of the suspect’s car is a good example.

Firearms Identification

All you CSI: Miami fans know that this is right up Caleigh Duquesne’s alley. Firearms identification involves the examination of firearms and the bullets they fire, including ammunition, shell casings, shotgun shells, and fired bullets. Police scientists use microscopes or varying types of chemical analysis to identify the type of gun used to commit a crime and match any bullets fired from that weapon or shell casings to a weapon of interest.

Document Analysis

Whenever an important document whose handwriting or authenticity is in question, a document analyst uses handwriting analysis to compare handwriting samples to questionable documents or signatures. Document analysis also may involve analyzing the chemical and physical properties of papers and inks or exposing indented writing–the indentations made on the page underneath one that was written on. In addition, document analysis also includes typewritten and photocopied documents that may have been altered.

Fingerprint Analysis

Fingerprint analysts compare prints found at a crime scene to the fingers, palms, or soles of potential suspects. A print found at a crime scene can be compared with another print stored in a database such as the FBI’s Automated Fingerprint Identification System (AFIS) or from a suspect, victim, or bystander.

Hopefully, all four of these aspects of physical forensic science will give you a clearer picture of what is involved. All law enforcement crime labs use these methods to help bring a crook to justice.

For those of you who are science buffs, this article is food for thought.

By: Fabiola Castillo

DNA In Forensic Science

admin — Sun, 16 May 2010 22:41:18 +0000

Since the introduction of DNA testing started to use as evidence in 1990, the criminal justice system has been improved but mistakes and human errors have downplayed the effectiveness of this DNA technology.

This DNA forensic has undeniably helped in solving tough cases and yet, public awareness of the information is only surface touching depth.

Forensic identification tests can link the DNA segments to each individuals existing.

Examples of DNA uses in the field include identification of potential suspects whose DNA maybe match leftovers at crime scenes, establishment of paternity and family relationships of victims whom could not be recognized based on their outlooks and matching organ donors with recipients in transplant programs.

The selected interesting cases of forensic identification which involved the DNA Shoah Project, identification of the 911 and South East Asia 2004 Tsunami victims.

There have been two main types of forensic DNA testing. They are often called; RFLP and PCR based testing, although these terms are not very descriptive.

Generally, RFLP testing requires larger amounts of DNA and the it must be under graded. Crime-scene evidence that is old or present in small amounts, is often unsuitable for RFLP testing.

Warm moist conditions may accelerate DNA degradation rendering it unsuitable for RFLP in a relatively short period of time.
PCR-based testing often requires less DNA than RFLP testing and the DNA may be partially degraded, more so than is the case with RFLP. However, PCR still has sample size and degradation limitations that sometimes may be under-appreciated.

PCR-based tests are also extremely sensitive to contaminating DNA at the crime scene and within the test laboratory.
During PCR, contaminants may be amplified up to a billion times their original concentration. Contamination can influence PCR results, particularly in the absence of proper handling techniques and proper controls for contamination.

PCR is less direct and somewhat more prone to error than RFLP. However, PCR has tended to replace RFLP in forensic testing primarily because PCR based tests are faster and more sensitive.
Science cannot yet provide conclusive results on genetics and behavior. Discovering more about ourselves to the basic components can reveal much more about us.

Blood group, originality, race, allergies, genetic dominance and other elements just showed that we are fascinating creatures to exist on earth.

By: J.J. Yong

The Science of Criminal Investigations – What is Studied in Forensic Science?

admin — Fri, 14 May 2010 01:42:15 +0000

Forensic science is one of the youngest sciences in the world. It focuses on the study of the physical evidence that is created by a crime or related event. Forensic science can lead to a number of professions that relate to the collection, examination and interpretation of physical evidence including medical examiner, crime lab analyst, crime scene examiner, forensic engineer, forensic psychologist, and technical forensic adviser.

Crime Scene Examiner

The first profession that many people think about when they think about forensic science is the crime scene examiner. This person is responsible for managing the collection and documentation of physical evidence at a crime scene. This person usually doesn’t analyze the data, as this is done by another professional. They instead are trained in how to protect evidence from becoming damaged, lost or contaminated. This career requires an understanding of physics, biology and of ballistics.

Crime Lab Analyst

The next career in forensic science is the crime lab analyst. This person is responsible for processing and analyzing the physical evidence that is collected. This person will utilize a variety of tools to examine the evidence including a microscope, chemical analysis tests and ballistic tests. They will also utilize their understanding of criminology in order to draw conclusions.

Medical Examiner

A medical examiner is a forensic scientist that has a medical degree. This doctor will examine a body to determine the cause of death in cases of suspected suicide or murder. The medical examiner may also examine bodies from car accidents and industrial accidents that involve a fatal injury. Their examination often times uncovers evidence that can be used to link a suspect to the crime or to other illegal activities like drug use and rape.

Forensic Psychologist

A forensic psychologist is a forensic scientist that has a psychology degree. There are several levels of degrees that you can obtain including a bachelor’s degree, a master’s degree and a Ph.D. in Forensic Psychology. Forensic psychology utilizes the sciences of psychology and criminology to complete specific tasks to help solve a crime. For example, they use special techniques to questions witnesses and criminals with psychological or emotional disabilities and witnesses that are children. They also utilize their understanding of psychological theories to create profiles for criminals that are still at large.

Forensic Engineer

A forensic engineer is a classically trained engineer that utilizes their skills to examine physical evidence at structural crime and accidents scenes. For example, in the case of a train derailment a forensic engineering may be called in to see if the train or track had been tampered with or to determine the cause of the “accident.” These professionals will also examine structural fires, explosion sites and industrial accident sites.

Technical Forensic Adviser

One of the newest careers to be spawn out of forensic science is the technical forensic adviser. This professional is skills in computer science. They use their computer background to find and analyze physical evidence of computer crimes like hackers and malware developers. The evidence that they collect and analyze are digital in nature and require special expertise in programming and IT systems.

By: Madeline Binder

The Science of Forensic Investigation

admin — Thu, 13 May 2010 15:58:00 +0000

The science of forensic investigation has been around for hundreds of years. In the past hundred years however, Forensic investigation has developed and the progress that has been made is astounding. The art of forensic investigation is used every day on crime scenes throughout the world. A forensic investigation refers to the investigation of a crime scene. A crime scene investigator reconstructs the crime scene, analyzing evidence and carefully documenting each one of their findings. If only one piece of evidence is documented incorrectly, it could put the whole criminal case in jeopardy, potentially setting a criminal free to run the streets.

Crime scene investigators are specially trained members of the police force. They are the first people on a crime scene, and only they can release any property or information once the investigation is completed. There are different types of forensics that fall into the category of forensic investigation. The most simple of type of forensics is fingerprint. This is when a crime scene investigator gathers finger print evidence from a crime scene and analyzes it to get a finger print match.

Perhaps the most recognized form of forensic investigation is DNA testing. This testing is done by testing physical evidence such as secretions or blood from a crime scene and testing it to determine if it belongs to the victim. It doesn’t, the sample will reveal certain genetic markers including the blood type of the unknown person. In cases such as assault, robbery, rape and murder, an experienced crime scene investigator is critical. They are trained in what to look for and how to test the evidence. Even the smallest piece of dust or a single hair can yield a wealth of information to a trained investigator. A single hair found at a crime scene can literally tell the investigator if they are looking for a male or female, or if the hair belongs to an animal.

A trained forensic investigator can take a half eaten apple and use the bite marks as identification, sort of like finger prints, thus catching a criminal who thinks that he or that they got away with a criminal act. A forensic investigator not only investigates murder scenes, their services are also used to detect forgeries by handwriting analysis, and testing water for purity.

Performing a forensic investigation is a long and complicated process. Every inch of a crime scene needs to be processed, starting with collecting finger print evidence from every inch of the crime scene. Once the finger printing is done, the more tedious task of collecting every bit of dirt, dust, paper, clothes, fluid samples and everything else that is on the scene. Often, it takes weeks to process an entire crime scene.

By: Carl Walker

Forensic Science Lesson Plans

admin — Thu, 29 Apr 2010 00:52:26 +0000

A lesson plan is a teacher’s detailed description of the course of instruction for an individual lesson. While there is no single way to construct one, most lesson plans contain some or all of the elements of the course. In today’s modern teaching style, individual lesson plans are often inappropriate. Specific objectives and timelines may be included in the unit plan, but lesson plans are more fluid as they cater to the students needs and learning styles.

Students are asked to engage in problems or inquiry learning. Rigid lesson planning with title, objectives and specific outcomes within certain time constraints, often no longer fit within modern effective pedagogy. Today, formal lesson plans are often required only by student teachers, who must be demonstrably familiar with the components of a lesson, or by teachers new to the field, who have not yet internalized the flow of a lesson.

Given below are a series of different lesson plans which may appeal to science professors, currently teaching forensic science in class, involving a range of difficulties and different aspects of forensic science.

Bloodstain Analysis involves introducing students to some of the techniques used by forensic scientists for analyzing blood, the concept of blood type, and providing opportunity for students to practice critical thinking skills in the context of scientific inquiry. It consists of two parts. The first part is intended to teach students about the catalase test, which is used to detect the presence of blood. While there are more sensitive tests available for the presence of blood that an investigator might use, this is by far the cheapest. Students are expected to predict whether or not the substances provided will be catalase positive or negative. They also examine whether each substance tests positive for blood using the phenolphthalein test. After this step, they open the evidence packets provided and test whether each stain that was found is likely to be blood or not. The second part addresses blood typing.

Hair Analysis intends to introduce students to the thought process involved in developing a technique for forensic analysis and to the physical structure of hair. It also provides opportunity for students to improve skills in observation, critical thinking and microscopy. This activity again involves two parts, which may be performed separately or as a cohesive unit. The first part requires students to examine a given set of hair. Using their observational and critical thinking skills, they develop a procedure to identify hair collected from crime scenes. The second part is intended to complement any crime scene scenario. In this part, students examine the hair supposedly collected from the crime scene as well as hair of the suspects and the pets involved. They use the data sheet provided to determine which suspect is the most likely match.

DNA fingerprinting involves the preparation and conduct of the DNA fingerprinting laboratory. It is divided into the following parts- Preparation of the student materials, plasmid DNA preparation, restriction endonuclease preparation, migration dye preparation and preparation, loading and running of an agarose gel for use with carolina blue stain.

By: Elizabeth Morgan

Fingerprinting in Forensic Science

admin — Sat, 06 Feb 2010 10:55:39 +0000

Fingerprints collected from a crime scene, or from items of evidence from a crime, can be used in forensic science to identify suspects, victims and other persons who touched the surface in question. Fingerprint identification emerged as an important system within various police agencies in the late 19th century. This system replaced anthropometric measurements as a more reliable method for identifying persons having a prior record, often under an alias name, in a criminal record repository. The science of fingerprint identification stands out among all other forensic sciences for many reasons because of its superiority and reliability.

Worldwide, fingerprinting has served all governments during the past 100 years to provide accurate identification of criminals. No two fingerprints have ever been found alike in the billions of human and automated computer comparisons. Fingerprints have become the very basis for criminal history foundation at almost every police agency.

The first forensic professional organization, the International Association for Identification (IAI), was established in 1915. It established the first professional certification program for forensic scientists, the IAI’s Certified Latent Print Examiner program in 1977, issuing certification to those meeting stringent criteria and revoking certification for serious errors such as erroneous identifications.

Fingerprints remain the most commonly used forensic evidence the world over. In most jurisdictions, fingerprint examination cases outnumber all other forensic examination casework combined. It continues to expand as the premier method for identifying persons, with tens of thousands of persons added to fingerprint repositories daily in America alone – far outdistancing similar databases in growth. Fingerprinting has outperformed DNA and all other human identification systems to identify more murderers, rapists and other serious offenders (fingerprints solve ten times more unknown suspect cases than DNA in most jurisdictions).

Although some reporters and authors claim that fingerprints have long enjoyed a mystique of infallibility, the opposite is true. Fingerprint identification was the first forensic discipline in 1977 to formally institute a professional certification program for individual experts, including a procedure for decertifying those making any investigative errors. Other forensic disciplines later followed suit in establishing certification programs whereby certifications could be revoked for any error found.

Fingerprint identifications lead to far more positive identifications of persons worldwide daily than any other human identification procedure. The American federal government alone effects positive identification of over 70,000 persons. A large percentage of the identifications, approximately 92% of US Visit identifications, are affected in lights-out, no human involved computer identification process with 100% accuracy based on only two fingerprints.

By: Elizabeth Morgan