Research Paper on "Forensic Evidence in Criminal Investigations"

Research Paper 5 pages (1843 words) Sources: 5

[EXCERPT] . . . .

Forensic Evidence in Criminal Investigations

This is a template and guideline only. Please do not use as a final turn-in paper.

The term forensic means, "relating to or dealing with the application of scientific knowledge (as of medicine or linguistics) to legal problems" (Merriam-Webster, Inc., n.d.). Forensic evidence consists of the objects or information gathered at a crime scene that can ultimately be used in a court of law to prove innocence or guilt. Forensic science studies this evidence for the purpose of providing scientific evidence, utilizing mostly chemistry and biology, but also including psychology, physics and many other disciplines.

Forensic evidence may consist of almost anything, whether it be the standard finger print, some form of DNA, blood, footprints, palm prints, hair, seminal fluid, clothing, saliva, urine, or almost any form of non-biological evidence. Police investigators may look at patterns of bruising on a victim and forensic science can tell them what the bruising is from and how it was done. Any injury suffered by a victim can be carefully analyzed. Recent sexual contact can be detected, and the consistency between the evidence and a victim's or suspect's account of events analyzed.

Weapons and ammunition can be analyzed utilizing modern technology and techniques. There is virtually no end to the reasons forensic evidence is so crucially important to today's crime investigations.

Forensic evidence is so critical to a modern-day police investigation that the first priority in any investigation is to "save" the crime scene -- to preserve it in pristine condition so that forensic and other evidence may be gathered without it being disturbed. For instance, if there is blood on a weapon that needs to be collected, it must be done so that nothing else, like a finger or palm print on the same weapon, is disturbed. If there are human hairs on the weapon or where the weapon is found, then those cannot be disturbed while the blood is collected and the finger or palm prints taken. It is a painstaking, long, slow process. Everything must be documented, located, and mapped so that exact locations of every tiny bit of forensic evidence can be identified and retraced (Layton, 2005).

Crime scene documentation is the process of creating that visual record so that the forensics folks and the district attorney can recreate it. Still photos, sketches, notes and video are taken to ensure that nothing is missed. Only after the scene is thoroughly documented can the actual finding and gathering of forensic evidence begin.

Now, the crucial role of forensic evidence begins to take shape in any police investigation. If any of the evidence is disturbed or unintentionally altered in some way, all of the evidence might later be suspect in court and a criminal could be set free. We identified some of the typical kinds of evidence often found at a crime scene, but others consist of:

Dead body

Trace evidence like gunshot residue, paint residue, broken glass, unknown chemicals, and drugs

Other body fluids like saliva or vomit

Documents like diaries, suicide notes, address books, and electronic documents

Examining the body is a critical part of any forensic procedure. A visual inspection and careful documentation is usually done at the scene and the medical examiner usually notes any stains or marks on the clothing or body, whether or not the clothing is in disarray and, if so, how,

Also important are any bruises, cuts or marks, defensive wounds, missing items of jewelry, blood loss and pooling, other bodily fluids present, and any insect activity on the body that might indicate time of death. The body is then removed to the morgue where a thorough examination and autopsy is performed.

A thorough, patterned search is then done of the entire crime scene, forensic evidence is preserved, bagged, tagged, and logged. Then it is all transported to the forensics lab.

In most large forensics and crime labs, several departments exist such as: latent fingerprints and impressions, trace evidence, chemistry, computer crimes, firearms identification, serology and DNA, and documents (Layton, 2005). Over the past decade or so, computer forensics has become a major part of police investigations to the point that most local agencies and federal law enforcement organizations also include some form of computer forensics lab as part of their crime labs.

Any particular piece of evidence may go through one or several departments and each department that examines it will give a complete report from their perspective. The results are then sent to the lead detective on the case. Of particular interest in almost every criminal case is the availability and results of the DNA test.

DNA evidence has advanced significantly since the mid-1980s, and is now a keystone of forensic science. It alone may significantly contribute to the conviction a person of a crime based on the presence of their DNA at the crime scene. It has also been used to help to free those convicted falsely of a crime. DNA is a biological molecule in the form of a long, twisted chain known as a double helix. It is made up of four nucleotides or nitrogen-bearing molecules and is wrapped into 23 pairs of chromosomes -- half of each pair originates with an individual's father and the other half with the mother. And forensic scientists know that, unless there is a twin, DNA is unique to each individual (U.S. Dept. Of Energy, 2009).

Forensic evidence in courts of law to convict an individual of a crime is used correctly in thousands of cases to send criminals to prison. But it can also be misused, abused, and misinterpreted by the best of experts so that innocent people go to jail, or, as in the case of Cameron Todd Willingham, and many others, are executed for a crime he did not commit.

Willingham was accused of murdering his three young daughters in Texas in 1992 after they died in a house fire while Willingham was asleep. He was convicted by forensic "experts" who claimed the father intentionally set the fire and by the false claims of a prison informant who said Willingham confessed. After his execution, a panel of the nation's top forensic experts reviewed all the testimony and forensic evidence and found that none of the scientific analysis used to convict Willingham was valid (innocence project, 2010).

And that is the point. It is the analysis of the forensic evidence that can either be incorrectly applied or used properly and objectively to present testimony at a trial. All the correct police procedures in gathering the evidence can go out the window if tests are accomplished haphazardly or analysis of those tests is incorrect. That is what happened with Willingham.

Forensic evidence is used at trial, usually with the assistance of an expert witness who can accurately and objectively testify as to the application and relevance of DNA found at the scene of the crime or on the weapon used to kill the victim. Expert witnesses are used for every aspect of the presentation in court of most forensic evidence since it lends credibility to the relevance of the physical object or crime scene situation being described. Without the expert witness, the forensic evidence can be wasted due to the lack of expertise and experience on the part of the individual attempting to explain it.

In order to see how forensic evidence is used to convict a felon we'll look at a brief generic case study of evidence found at the scene and how the evidence is combined to use at trial.

Let's pretend Type O blood is discovered at a crime scene. This type of blood is present in less than half of Americans -- about 44% to be more accurate. In addition, a blond hair is found which does not belong to the victim, who is brunette. The type of blood only limited our potential criminals to half the population, and the fact that he or she is blond limits it further.

But we now have two pieces of evidence. The detectives find a partial footprint in some of the blood at the scene, and, through investigation and database search, discover the footprint is from Nike Air shoes. Three separate pieces of evidence start to narrow the field of candidates.

This is the way forensic evidence is used to convict. The accumulation of evidence and the linking together of this forensic evidence becomes a strong chain to link the defendant to the crime scene. It is this chain of evidence, not any single piece, that most judges will instruct a jury to consider in whether to convict or not. And that includes DNA.

DNA is part of this chain. The same kind of logic is used as with the rest of the evidence. It is not usually the case that DNA alone is accepted as the sole factor to convict. Lab experts look for the number of matches in the individual's DNA sequence. One or two matches are not enough to identify the suspect without… READ MORE

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