Detecting Evidence After Bleaching

Most people know that forensics involves many different kinds of evidence, whether that is blood evidence or a weapon. However, the evidence can become degraded from a number of things such as time, heat or the use of bleach. Unfortunately, even advanced Forensic Techniques can be challenged by the use of a common kind of bleach found in many homes.

Understanding Bleach and Evidence

To understand how it all works, you have to consider that there are two kinds of bleach that are found in the majority of cleaning products within your home. There are bleaches that are primarily chlorine and there is also oxygen bleach.

Chlorine bleaches can remove a Bloodstain to the naked eye but fortunately, forensics experts can use the application of substances such as luminol or phenolphthalein to show that haemoglobin is present. In fact, even if the shady criminal washed a bloodstained item of clothing 10 times, these chemicals could still reveal blood.

With oxygen bleach, the bleach has an oxidizing agent, which could be a substance such as a hydrogen peroxide. In these instances, haemoglobin is completely removed and can't later be detected. As expected, this presents a unique challenge for forensic scientists. Not only that, but it can significantly compromise an investigation and may mean that Evidence is not properly investigated and used in a trial.

Testing Out Bleaches

To properly assess whether bleach could fully remove blood, researchers soaked some bloodstained clothing in oxygen bleach for a couple of hours. After the bleaching, stains did look faded, although they were still somewhat noticeable. On the other hand, even though there was some visible marking, luminol and phenolphthalein didn't detect the haemoglobin on the clothing.

Challenges of Detecting Bleach

The results are worrying because a stain on clothing could be assumed to occur from something else when a test shows up negative for haemoglobin. Eventually, valuable evidence could ultimately be dismissed, which then affects the entire criminal investigation and trial proceedings.

Forensics experts will not examine and check for important DNA Evidence until they have initially found an appropriately identified blood sample. In this way, the entire investigation is compromised and the opportunity to obtain more information is lost.

Fortunately, there is a better chance of obtaining useful information from the seams of clothing. While washing does remove a great deal of evidence in the rest of the garment, it is far more challenging for a criminal to remove evidence found in the clothing seams.

Improving Forensic Science

The study is an important one that highlights the limitations and scope of forensics techniques in science today. Clearly, we have many advanced and sophisticated tools to investigate blood evidence.

Yet, science can't always compete with materials used to remove these stains, such as oxygen bleach. However, it is at least a positive step that we can identify these challenges, which means that efforts can be focused on finding ways to overcome them and identify blood even after all kinds of bleaching. In the end, this is good news for forensics but bad news for criminals.

New Ways to Detect Lies with Forensic Science

One of the most challenging tasks for a forensic expert is determining if a person is telling the truth. Over the years, all sorts of testing methods have been introduced – some eventually disregarded while others have become mainstays in Forensic Science.

New Techniques

In the past several years, however, new techniques have been brought forth, many promising to revolutionise the way in which we determine if a person is honest or telling a lie. In fact, a recent claim is that a new test is 97% accurate in finding out if someone is telling lies.

Does It Work?

The test has, however, been approached with much scepticism and doubt. The technique is one that monitors the brain using functional magnetic resonance imaging (fMRI).

Researchers in support of the test claim that it is the gold standard for determining if a person is lying. Those who developed the technique cite that when a person is lying, there is an increase in blood flow to the brain. In turn, oxygen levels in the brain increase.

What the Scan Shows

In terms of what the researcher can see, the scanner shows that areas of the brain essentially brighten when questions are asked. The test was developed in the United States and researchers believe that it's tougher to 'cheat' the fMRI than the traditional polygraph because the fMRI keeps track of changes in the brain, as opposed to the usual stress responses that link up to a lie.

The approach to testing is different as well. Rather than bombard the person being tested with a constant barrage of questions, the person receives more segregated questions that are asked in smaller bits. In this way, the brain can basically recover from the last question, allowing it to go back to 'normal'. Then, the next question can provide a result that is more accurate and easier to read.

Bringing the Test to the Market

At present, the lie detector technique is available on a commercial basis in the United States. In fact, the technique has even been utilized by a forensic team investigating a crime. The aim is for the technique to be widely adopted around the United States as well as in Canada and Europe.

Unfortunately, there is still some controversy around the test. Queries have been raised about whether or not this test is ethical and there are issues around the level of invasiveness of the test. Its accuracy is also still under question, which means that routinely using it in court may still be a long way off.

Future of Lie Detection in Forensic Science

Lie detection has been a challenge for decades in terms of forensic science. While it seems that there are many different kinds of techniques available, discerning which ones are accurate and reliable is an immense challenge. Given the use of these tests in the criminal justice system and their ability to change lives when they are used as evidence, we have to be extremely careful when evaluating any new technique for lie detection.

Using Lie Detection

The idea of implicating someone in a crime when they are innocent is a real fear that has to be examined before deciding to use a specific lie detection technique. However, it's promising and positive that we do have ongoing research into this area. Indeed, if the new test is as accurate as it purports to be, it could be a very important technique for helping us identify criminals and bring them to justice.

Estimating the Time of Death

Estimating the time of death for the deceased is something else that the pathologist will have to do during the course of his autopsy procedures. In addition to this he or she may be called upon at the scene of a crime whilst carrying out their external examinations to try and judge - or best guess - when the victim died.

At the Scene

It may sound silly but one of the first things to do once a crime scene has been secured and all relevant details documented; is to check for a watch. If the victim does have a watch is it broken? If it is then the watch will more than likely have stopped at the time of the individual's death, especially if they have had a heavy impact or long fall.

It must be said however that the time the individual took their last breath is not necessarily the time at which they died. This may sound bizarre but taking into consideration the human body can function for a period of time without oxygen - the human brain reportedly surviving several minutes without it - then it is reasonable to assume that the time of death may not always be accurate.

Categorising Time of Death

Time of death is categorised in three ways:

• Physiological time of death: The point at which the deceased's body - including vital organs - ceased to function.
• Estimated time of death: A best guess based on available information.
• Legal time of death: The time at which the body was discovered or physically pronounced dead by another individual. This is the time that is shown - by law - on a death certificate.

Methods Used

One method of estimating the time of death is to measure body temperature. The normal equation for this is:

• 37.5oC - 1.5 oC

This formula equates to the body temperature (37.5oC), which loses 1.5 oC per hour until the temperature of the body is that of the environment around it; known as the ambient temperature. This ambient temperature - depending on how low it is - may take minutes or hours to be reached and this is a good indicator as to how long a body has been in situ. Additionally it is worth noting that a body's temperature will drop much more slowly if the body has been exposed to extreme cold; such as being left outdoors, submerged in water or icy conditions.

The most common way of taking the temperature of the deceased is to use a rectal thermometer or to take a temperature reading from the liver, which can achieve a more realistic core body temperature.

Rigor Mortis also acts as a good measuring stick for estimating the time of death. This natural process which occurs in all of us when we die and is the natural contracting and relaxation of the body's muscles caused by changes in the body's chemical balances.

Rigor normally occurs in the smaller muscles such as those in the face and neck and will work its way down through the body as the muscles become larger. The process normally begins roughly two hours after death and can last for anything from twenty to thirty hours. It is a common misconception that rigor does not leave the body; it will after these time frames have elapsed.

Rigor is one of the most used ways of estimating death as it occurs in the body during the first thirty-six to forty-eight hours.

Forensic Entomology (the study of insects) is another way in which the time of death can be estimated. By studying the insects found at the crime scene the pathologist is able to establish a more accurate time scale depending on which insects are found on the body and what stages they are at in their life cycle. To find out more read our article on Forensic Entomology.

Forensic Science

Forensic Science

To put forensic science in simple layman's terms: it is the application of scientific procedures in conjunction with the law. Forensic science is the umbrella term for a collection of scientific procedures that can be employed when it comes to providing evidence that a crime has been committed and also provides ways and means of proving how a crime has been committed.
In its simplest form, it can be a means by which fingerprints, fibres, DNA and bodily fluids can be collected and stored - without contamination- so that they can be later used as
evidence in a police investigation into a specific
crime - or indeed a series of crimes.

Types of Forensic Science

Forensic science breaks down into the categories of:

• Forensic Science
• Forensic Medicine
• Forensic Psychology
• Forensic Dentistry
• Forensic Graphology
• Forensic Accounting

Each of these categories will at some time or other be employed in a criminal investigation and can also be used in commercial matters such as insurance investigations, allegations of fraud and/or corruption, and proving the paternity of an individual in an ongoing investigation relating to child welfare.

Forensic Science and Crime

All of these categories have their own particular specialities and it is important to recognize that the role of Forensic Science in the area of criminal prosecution has proved vital in bringing many criminals to justice who might have otherwise slipped through the net.

It is important to remember also that Forensic Science is not simply investigating the events surrounding and leading up to death. It is also used to prove that serious sexual and grievous bodily assaults have taken place and it has proved fundamental in how the legal system conducts cases once they have been brought before a court of law.

Forensic Science Developments

In the last two decades forensic science has seen many important discoveries made and has had many different procedures added to its remit in order to aid in the detection of criminals and also in proving the innocence of people suspected of crimes they did not commit.

Indeed, without forensic science, it is fair to say that many of the crimes that are committed today in our world would go unsolved and most definitely unpunished if it were not for these advances.
Forensic science has now become a scientific study in its own right and now includes some of the world's most important discoveries as part of its remit.
 These include:

• DNA coding
• Toxicology - the study of drugs and their effects on the human body
• Serology - the study of bodily fluids
• Ballistics - the study of firearms

In addition to these studies forensic science also looks at the time of death, cause of death and how a body is disposed of. It also takes into account the fact that bodies many not necessarily have died where they are located and techniques within the field can provide definitive proof of this through soil analysis, examination and categorizing of various pollens, and many other factors such as temperature and weather conditions.

It is fair to say that forensic science has become one of the most important areas of the scientific study of the 20th and 21st century and will remain so for a long time to come.