The driving force of art forgery is the fact that art work created by certain artists is worth more than art work created by others.  If a work of art can be replicated perfectly by an art forger it is only worth less monetarily than the original because of who painted it not because the painting looks any differently than the original.  The same theory applies to forgers who create new art pieces in the style of a master, if the forgery is believed to be genuine it will be deemed priceless but if it is found to be a fake it is deemed worthless, regardless of what the piece of art looks like.

Forensic investigators, along with art historians and appraisers, are often responsible for determining if a piece of art is a forgery or not. Historians often use stylistic analysis to determine if a work of art is genuine or not, possessing large amount of knowledge about the styles, tool, brushstrokes,  techniques used by certain artists. There are a variety of methods used for forensic authentication of art work.   Some of the technical methods for revealing fakes include X-rays, UV lights, and IR light, which can be used to see under layers of paint to see covered up works, determine time period or the actual artist of the painting if an original signature has been covered up.  Chemical analysis and spectral comparisons can detect the components of paint to ensure that modern pigments were not used in supposedly old paintings.  Examination of the craquelure, the network of cracks that appear on old paintings, can be analyzed to ensure that the cracks were not artificially made and that they follow the grain of the wood onto which they were painted.

Art forgery sounds like a thing of the past, but art dealers claim that about 15% of art sold at auctions are fake, which means hundreds of people getting conned out of thousands of dollars.

For more information on art crimes  save the date, the Museum’s new art crimes temporary exhibit is coming on February 15th, 2010!

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Hair can yield DNA evidence, if hair is pulled out by the root, as in some violent struggles, it will contain root pulp which is a good source of nuclear DNA (nDNA), the type of DNA most often used in forensics.  The hair shaft does not contain nDNA, so the 100-150 strands of hair most people lose daily will not contain a root or nDNA, but it does have mitochondrial DNA (mDNA).  MDNA, which cannot be used for individualization, can narrow the source of the hair down to a certain family group (mDNA is passed from mother to all offspring).

Hair can also be used to run drug tests, but these tests are only presumptive and have to be confirmed by blood or urine tests.  Hair absorbs chemicals, such as marijuana smoke and arsenic, from the environment and once the chemical is in the hair there is no way of telling if it got there from consumption or from exposure from the environment.

Age cannot be determined from hair, generally the only age determination that can be made from hair is if came from an infant or from an elderly person.  The sex of the person the hair came from can also not be determined via hair examination unless there is nDNA  evidence such as the root.

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The big question today is how reliable bite-mark evidence is.  Bite-mark evidence has been used to convict a number of people, but has, with the advent of DNA, been proven to do so wrongly in a number of cases.  Many cases have surfaced in which people have been convicted of a crime using bite mark evidence and have been exonerated, unfortunately years later, using DNA.  In fact, a 1999 study found a 63% rate of false identification using bite-mark evidence.

Bite-mark analysis works much like shoe impression or fingerprint analysis, both class and individual characters are examined in order to make a positive ID.  The class characteristics for bite-marks, which narrow down evidence as belonging to a small group, include size, shape, and bite of the teeth. Individualizing characteristics of bite-marks, accidental traits that make the bite-mark impression unique to one person, include fractures, wear, and congenital malformations of teeth as left behind in the bite-mark impression.  So why is bite-mark evidence proving to be so unreliable?

Bite-mark evidence is mainly at issue when it involves the human skin.  Most of the problems come from some of the basic characteristics of skin.  Skin shifts when it is bitten, skin also stretches in different ways when a person is in different positions, so if the victim was moving and the skin was shifting during the bite incident how accurate of a pattern can the bite-mark leave behind for comparison?  Another factor that can influence the bite-mark and its examination is time.  One must consider how much time elapsed between the infliction of the bite-mark and when it is to be examined for comparison.   The natural healing and bruising process changes the skin and the wound over time, changing the pattern as it heals.

Given these uncertainties, many agree that bite-mark evidence, particularly on skin, is mainly helpful in excluding suspects but should not be used as an individualizing tool.   Everyone one agrees that the most important tool for examining a bite-mark is a DNA test. The saliva from a bite-mark, more than anything else, can be used to make a positive match to a suspect.

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Although it is thought that each person has a unique OAE in response to auditory stimuli there is not a way of distinguishing these low frequency sounds to the point of use for identification….yet.  Once the technology is developed for recording these emissions the OAE can be recorded with a simple device placed next to the entrance of the ear such as telephone handsets or headphones.  Some of the potential applications include identity verification for call centers dealing with sensitive transactions such as during phone banking.

OAE’s are already in use by hospitals and physicians to scan for hearing damage as well as defects in newborns and children since OAE’s disappear if damage exists in the inner ear. This is also one of OAE’s potential downfalls.  Not only do OAE’s disappear when the inner ear is damaged, but colds, medication, and trimming one’s ear hair may alter a person’s OAE as well.

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Fingerprint residue contains natural salt secretions that corrode metals at the points where the salt contacts the metal. This microscopic fingerprint corrosion leaves a permanent mark on metal that cannot be washed away. The heat of the firing of the gun also does not alter these marks.

The new technique that has been established to visualize these types of prints relies on running electrical current over the metal object , such as a bullet casing or a gun, that has been coated with a fine toner like powder. When a charge is run down the metal object the fine conducting powder is attracted to these areas of corrosion revealing a powdered fingerprint.

This technology can also be used in fires to recover prints of metals exposed to very high temperatures.

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When light is shined on a surface, the surface can either absorb, reflect, or transmit the light. In special situations, the light that is shined on an object is absorbed by that material and then re-emitted at a different wavelength (called a Stoke’s shift), which is known as fluorescence. Typically when an object fluoresces, the light is re-emitted at a lower energy state, and therefore, at a longer wavelength. In the case of blue light as the incident light, the re-emitted fluorescence usually occurs in the orange spectrum – that’s why investigators wear orange goggles! In order to see the faint fluorescence, investigators must block out all the blue light from entering their eyes since that would drown out the faint fluorescence, so orange goggles will only allow orange light to reach their eyes, and hence, the fluorescence is observed.

Many body fluids, organic materials and fibers will fluoresce under the forensic light source, and other materials such as blood, gunshot residue, and some inks will absorb blue light to appear dark under the light source. These substances are often not observable to the naked eye, and especially if the surface was wiped down or cleaned. The forensic light source is always a good starting point in a crime scene search because it is portable, quick, cheap (once the unit has been paid off), and most of all, non-destructive, meaning that it will not damage or harm any of the evidence.

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Play our New Trivia Game Now!

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Read about how different states handle the death penalty here

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• Fingerprint science “does not guarantee that two analysts following it will obtain the same results”.
• Shoeprint and tire-print matching methods lack statistical backing, making it “impossible to assess”.
• Hair analyses show “no scientific support for the use of hair comparisons for individualization in the absence of (DNA).”
• Bullet match reviews show “scientific knowledge base for tool mark and firearms analysis is fairly limited.”
• Bite-mark matches display “no scientific studies to support (their) assessment, and no large population studies have been conducted.”

The art of fingerprint comparisons

There is no denying that a fingerprint examination is a subjective process. When an examiner conducts a common source determination, he or she will compare points of individuality in the two prints and evaluate if their is sufficient quantity and quality of detail in agreement between the unknown and the known prints to reach a conclusion. These assessments are largely based on the examiner’s interpretation of the evidence, and there are no specific measurements or standard tests to benchmark against, except for counting the number of points in agreement. In the U.S., the courts deliberately eliminated a threshold standard of agreement, so that the determination can remain a subjective matter, taking into account the examiner’s training and experience, and both the quantity and quality of comparable details. That is to say that an examiner does not have to observe a minimum number of points in agreement between the unknown and the known print to reach a common source conclusion, but can rely of his or her specific training and experience to guide the examiner to the right conclusion.

As you may have gathered, an element of a fingerprint comparison is dependent on the person doing the examination. An examiner needs to be able to see the fingerprint in a specific way, store that in his or her memory, and then recall it when comparing it to another fingerprint. A person’s ability to recognize shapes, small details, and other spatial relationships is crucial to the job of a fingerprint examiner, and can be considered an art form. It is a learned skill, requiring practice and concentration, and one that is ultimately susceptible to variation.

So, if fingerprint examination is an art, where is the science?

The science of fingerprint comparisons

Fingerprint examinations are deeply rooted in scientific principles. The whole fingerprint field is based on the recognition that no two people will ever have the same fingerprints, and that an individual’s fingerprints will remain unchanged throughout life. Based on these premises, the science of fingerprint comparisons is one that should, in theory, have no error. Either a fingerprint found at a crime scene is the same as the known print or it is not – there is no in-between. The examiner’s methodology is also based on the scientific method. An examiner follows the ACE-V methodology for fingerprint comparisons, which is an acronym for the stages of the examination. Analysis is the first step, where the examiner will look at the unknown print and determine if there is sufficient quantity and quality of friction ridge detail to be able to conduct an examination. Next comes the comparison, where the examiner will look for class and individual characteristics in the unknown fingerprint and compare them with the known prints. In the third stage, the examiner will evaluate the comparison, determine how much weight to attribute to the different similarities and dissimilarities between the prints, and reach a conclusion. The conclusion an examiner can reach is either exclusion (the prints came from different sources), individualization (the prints came from a common source), or no conclusion (there is insufficient amount of information to be able to reach a conclusion). The final stage is the verification stage, where a second examiner will conduct an independent examination on the same evidence and verify the first conclusion. Technically speaking, the examiners should reach the same conclusion since the science behind the examination should lead them to the same results. In this way, fingerprint comparisons should be reproducible and accurate because they are founded on scientific principles.

Understanding the argument

So, why does the report state that fingerprint science “does not guarantee that two analysts following it will obtain the same results”? Well, because essentially it does not. The emphasis on that statement is on the word “guarantee”. Whenever humans are involved in anything, there is the chance for error, even though in theory there should not be any for fingerprint science.  The tone of the statement indicates that each time an examiner conducts an examination on the same evidence there is an equal chance that they will each reach a completely different conclusion, but the science dictates that they should reach the same conclusion every time. Should that discredit fingerprint science? Some people believe that it should, especially since the error rate for fingerprint science has not been uncovered. The scientific community goes through great lengths to try to eliminate human error, by instituting random proficiency testing, continuing education, and board certifications as some of the measures to reveal the human error rate and to prevent unqualified individuals from becoming experts in the field. But as we have previously discussed, there is a human element to fingerprint science that even the courts have promoted as being crucial to allowing fingerprint examiners to do their job effectively. In fact, there are automated forms of fingerprint comparisons, such as AFIS (Automated Fingerprint Identification System), which is used to scan databases for a fingerprint match; however, the computers are not “authorized” to conduct an examination en lieu of humans, since the computers can not go to court and testify as to the reliability of their examinations. The U.S. has still mandated that a fingerprint comparison must be done by a person, since that is the most reliable way of ensuring that it is done properly. Computers can not deal with variation like humans can and they can not explain differences that are present in fingerprints from the same person. These philosophies dictate that a system that is too rigid is actually detrimental to fingerprint science, since it restricts the degree to which a person’s training and experience can contribute to a fingerprint comparison.

That leaves us with a “Catch 22”. On the one hand, humans are seceptible to error, even if measures are taken to eliminate those errors. On the other hand, computers, which do not make errors, are not qualified to do fingerprint comparisons. So, we are left with a situation that demands perfection from imperfect beings. While that does not justify the fact that errors occur, it should help us understand why they may occur and it should be a force driving us to reach perfection in our profession. I agree with the report’s call for more research in the human error rate, proficiency testing, advanced training, and stringent certification of examiners and labs, but let’s take the argument into context and understand how it can effectively be applied.

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Breanna Woodside – Cops say Breanna’s father, Miles Woodside, failed to return her to her mother as required in a custody order. Police say Miles Woodside should be considered armed and dangerous.

Haleigh Cummings – Cops say Haleigh was last seen in the area of Hermit’s Cove in Satsuma, FL wearing a pink shirt and underwear.
 

 If you have any information, or to report a tip, please click here to go to America’s Most Wanted website.

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