The Importance of Forensic Botany and How it Relates to Forensic Science - Research Paper Example

Forensic Botany Any science which is used for the purpose of law and which therefore assists in providing evidence for civil and criminal court cases is forensic science. It is a multidisciplinary subject, drawing principles from chemistry, biology, physics, botany, geology, psychology, sociology etc. Botany has been an inseparable part of forensic science since 1934, typically known as forensic botany. Traditionally, morphological aspects of botanical specimen identifications were used to provide evidence, but the last two decades have relied comprehensively on the molecular biology side of the botany. Contemporary history is the written evidence of the development in forensic botany; from wood identification to MALDI-TOF-MS (Matrix-assisted laser desorption/ionization mass spectrometry) of pollen grains. Success and failure of forensic botany had their own contributions to these developments. Like any other methodology, forensic botany has its own limitations, but scientist promise a brighter future, provided police and investigators gain more knowledge of the subject and work more closely. A ‘flawless’ crime is planned and executed. The perpetrator leaves the crime scene, hoping and thinking that he has left nothing behind. But he is seldom correct. There is an invisible and silent witness to the crime. It is called forensic science or just ‘forensics’. Forensic science is the application of scientific methodologies to legal problems and criminal investigations. Forensic science is not an independent study but an amalgam of several sciences. It includes works of pathologist, entomologist, mathematician, statistician, artists, engineers, doctors, biologists, and botanist; to name a few. Although our ancestors did not know forensics in its current form, it still existed in those days. Out of 23 blows inflicted upon Julius Caesar in 44 BC, only one was fatal, the one close to his heart that took his life. This was forensic science. A physician named Antistius, probably conducted the first recorded autopsy on Julius Caesar and came to the above conclusion (Et tu, Julius?). Forensic science existed in ancient history and so it does today, only improving over time as new developments occurred in this field. Scientists from various fields have contributed to its development as listed below. In the contemporary history, in 1950, American Academy of Forensic Science was formed. In 1953, world saw the double helical structure of DNA for the first time, as published by Watson and Creek; next year saw the invention of breath-analyzer by R. F. Borkenstein. In 1955, Gerald Samuel William de Saram studied temperatures of executed prisoners; a landmark study that helps to estimate the time since death. This occurs by a process of heat loss. A calorimetric method was developed by Harrison and Gilroyin in 1959 to check for gun powder residue from the shooter’s hands. In 1960, gas chromatography techniques for the identification of petroleum products used as accelerants in suspected cases of arson was introduced by Douglas M. Lucas. Analysis of blasts, fire explosions or fire debris is important to see if the fire was set intentionally or not. Forensic serologist Brian G.D. Wraxall co-developed immunoelectrophoretic technique for haptoglobin typing in blood stains in 1966. In forensic science, typing haptoglobin (Hp) in bloodstains is valuable because of its stability. Brian J.Culliford publishes a 270 page book in English titled “The Examination and Typing of Bloodstains in the Crime Laboratory”. The book was published in Washington by the National Institute of Law Enforcement and Criminal Justice in 1971. In 1974, X-rays were used to identify the gunshot residues using scanning electron microscope. In 1976, scientists William Keith Hadley and J. A. Zoro, of England, first suggested the use of gas chromatography/mass spectroscopy for forensic purposes. This technique helps to identify minute substances in case of explosion, arson, environment analysis or detection of drugs. Automated Fingerprint Identification System (AFIS), a biometric identification, with first computerized scans of fingerprints is introduced by FBI in 1977. In 1978, Electrostatic document analysis is developed to check document impressions. It is made by Foster + Freeman, UK. Variable number tandem repeats (VNTRs), are regions of DNA that do not code for any proteins but are highly variable amongst individuals, were discovered in 1980 and were later (1984) used for DNA finger printing by a British geneticist, Sir Alec John Jeffreys, of the University of Leicester. In 1986, Kary Mullis took off lot of load from molecular biologists by discovering polymerase chain reaction (PCR). This technique helps to make several copies of DNA from a single piece of DNA. In 1987, DNA profiling or genetic fingerprinting is used for the first time in US criminal court. A man was convicted of unlawful intercourse with a mentally challenged 14 year old girl, who gave birth to his child. The world’s first national DNA database comes into operation in1995, which was the biggest breakthrough in the fight against crime since fingerprints. This happened in UK, following a Royal Commission into the criminal justice system. In 1998, National DNA Index System (NDIS), a FBI DNA Database that enables interstate cooperation in linking crimes, was put into practice in USA (History of Forensic Science, Timeline, Key Dates). Twenty first century, so far, has however improved upon what was achieved in last fifty years or so in terms of technology and collaborations amongst forensic agencies of different states in a country and amongst neighboring countries in a region. It is a general belief that perpetrator always take something from the crime scene or leaves behind something. And when this ‘something’ is ubiquitous, it can be very rarely missed. Plant remains are found everywhere and hence they offer multiple sources of evidence. They may be visible to eyes like wood, leaves, roots, seeds, grass, flowers, and twigs or may be microscopic like spores, pollen grains, or aquatic algae and diatoms. Plants provide us with evidence because plants have anatomy, components, ecological requirements, habitat, and climatic requirements that are species specific. Plants and its components have varied morphology and this morphological diversity in plants help us to identify them, and such identification can help us to put the suspect at the crime scene. It can help to narrow down the geographical region where the crime occurred, the season in which a crime occurred, if a drowning occurred in domestic water or marine waters, how long a body has been lying at a particular place, is the crime scene and the body recovery scene the same or when was a grave dug. From wood anatomy to plant DNA “finger-printing”, today forensic botany has several subdivisions: palonology, limnology, ecology, anatomy, systematics, dendrochronology, and molecular biology. Palynology is the study of fossil and modern pollen grains, spores, and other acid-resistant microorganisms such as dinoflagellates, acritarchs, and chitinozoans (Bryant & Mildenhall, 1990). Limnology is the fresh water ecology, for example the study of algae and diatoms. Dendrochronology is the study of tree rings, which gives the age of a tree. Systematics is the study of evolutionary relationship amongst plants. The first botanical testimony to be heard in a North American court concerned the analysis of the wood of a ladder used in the kidnapping of Charles Lindbergh Jr. and led to the conviction of Bruno Hauptmann for the crime in as early as 1935 (Graham 1997). The child was kidnapped from his second-story nursery on the evening of March 1, 1932. A wooden ladder was used for this purpose. Arthur Koehler, a wood identification expert (Xylotomist) provided evidence against Bruno Richard Hauptman, who was later convicted of the crime. Koehler first identified the four trees species used to make the ladder. He then analyzed the tool (plane) marks left on the wood by the suspect and the lumber mill. The marks matched with those of the hand plane used by Hauptman. The ring and knot pattern on one of the ladder rail matched with a section of wood used in Hauptman’s attic; meaning that a portion of the attic wood was used to make the ladder. In this case of 1935, wood anatomy and wood systematics were used to convict a killer. Another example of 1959 illustrates the use of pollen grains to convict a killer. An Austrian man disappeared in Vienna along the river Danube, but his body was not recovered. A suspect with motive of killing the victim was found, but the police had no evidence to link him to the crime. There was no confession or a body. During investigation, a pair of boots was found in the suspect’s room, covered with mud on the sole. Wilhelm Klaus, a geologist with the Austrian Geological Survey analyzed the mud and found modern spruce, willow, and alder pollen. Also a special type of 20 million-year-old, Miocene-age fossil hickory pollen grain was also found in the mud. Such a mixture of pollen was found only in a small area north of Vienna, along the Danube valley. Dr Klaus was able to pin-point the exact location where the suspect might have got that mud onto his boots. When confronted with the identity of the location, the suspect confessed to his crime (Erdtman, 1969). Pollen grains have since been used to solve several cases in 1960s and 70s, for example a case in which pollens were used to indicate that the gun used as a murder weapon was used around the time of murder and not when the suspect claimed to have used it last for cleanup. The grease of the gun had pollens of alder and birch, which pollinate during the period when the murder took place (Palenik, 1982). In another case of same era, pollen grains were used to prove that a document claimed to have been signed in June, was actually signed in fall. The fall-pollinating pollen grains got stuck to the ink used to sign the document (Newman, 1984). Although in these cases pollen grains proved to be useful as evidence, most pollen based results are not precise, their results and interpretations are only circumstantial (Bryant & Mildenhall, 2011). Its usefulness is based on its ability to associate a suspect with crime scene and then only imply that the suspect may have been associated with the crime. This is one of the reasons pollen data have not been utilized more widely as evidence in court. “Pollen evidence is not like DNA fingerprinting where one might be able to state the probability of two samples being identical is one in a million or more. Although each pollen assemblage is unique in its own way, it is difficult to illustrate this point” says Professor Vaughn M. Bryant, from the Texas A&M University (Bryant & Mildenhall, 2011). The authors say that many complex mathematical calculations, additional time- consuming analyses of many pollen control samples and relying on computer- generated programs to show statistical probability are required to come to any conclusion and the court needs to know all of this. In the Austrian murder case (described above), the presence of an ancient hickory pollen grain found by Dr Wilhelm Klaus, known to exist only in one locale along the Danube River valley, became the “trademark” that made it possible to find a precise geographical location. Not all scientists can be this lucky. The good news is that matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF-MS) has been developed to identify and classify (using multivariate statistics) pollen grains. This technique will soon make it possible to identify pollens online (Krause, Seifert, Panne, Kneipp, & Weidner, 2012). This is yet another achievement and commitment towards the development of forensic botany and to overcome the limitations of pollen studies. The traditional forensic botany methods included species identification based on morphological characteristics of the specimen associated with the crime scene. But the last two decades have advanced a step further to include molecular strategies based on DNA identification. This has become possible with the advent of new technologies like real time polymerase chain reaction (RT-PCR), amplified fragment length polymorphism (AFLP), randomly amplified polymorphic DNA (RAPD), and MALDI-TOF-MS. Plant anatomy and plant systematics in the kidnapping and death of Charles Lindbergh’s young son in 1932, was a case that had used traditional methods of morphological identifications to prove a case in the court. However, the first criminal case that used plant DNA typing to gain legal acceptance was a homicide that occurred in Arizona’s Maricopa County, where RAPD was used to convict Mark Bogan of murder of a woman. In this case, in early May of 1992, body of a deceased black woman identified as Denise Johnson was found in Arizona desert. It was lying under a tree called Palo verde (genus Cercidium ). A beeper was found near the body which belonged to the suspect, Mark Bogan. Seed pods of Palo verde were found from Mark’s truck. Dr Timothy Helentjaris from the University of Arizona used a technique of Randomly Amplified Polymorphic DNA (RAPD) analysis to generate a band pattern of the specimen from the two locations. Since these band patterns are unique to this species of trees, Mark was convicted of murder by the virtue of having been placed at the crime scene. Bogan was sentenced to life in prison, which was upheld by an appellate court in 1995 (Carita, 2004). In another case where a PCR-based RAPD was used was in Southern Finland in late 2001. A man was found dead, about 5 km away from where he last met his three criminal friends and was seen together. The three suspects’ clothes, car and shoes were examined. Small pieces of botanical material called bryophytes or mosses were recovered. These samples were the only evidence that could link suspects to crime scene and the victim. A PCR-based RAPD technique consisting of oligonucleotide primers and simple sequence repeat primers (SSR) was used to identify the plant samples. Since one of the moss reproduced through sexual means, considerable genetic variations made it difficult to analyze using this DNA typing method. These results were included in the evidentiary samples. (Carita, 2004). Microsatellite markers or short tandem repeats or simple sequence repeats usually used for reproductive and demographic studies of native plants, have also been used as evidence in an attempt to link suspects to crime scenes. In a case of double homicide; a pregnant woman and her full term fetus were found in a shallow grave in woods of central Florida. Three large sand live oak trees were found in close vicinity of the grave. Two oak leaves were found from the suspect’s car. The suspect denied being present at the burial site. Scientist wanted to place the suspect’s car at the burial site. DNA was extracted from the leaves and PCR was done. Difference in the PCR product size reflects changes in the number of microsatellite repeat units. Variations in the number of alleles, heterozygosity and gene diversity were calculated to identify the leaves. However, the DNA profiles of sand live oak leaves taken from the suspect’s car did not match those of trees near the gravesite, and could not provide physical evidence in this particular case. This is a case of failure of botanical specimen to produce genetic evidence that could have placed a suspect at the crime scene. (Craft, Owens & Ashley, 2007). This case exemplifies the limitations of the evidence with advancing technology. For all molecular identification system, correct/ incorrect identification of a sample at a specific taxonomic level is an important consideration. If a sample lacks a representative at a genus or species level, then misidentification can occur. This could be due to PCR failure or PCR generating DNA fragments of inappropriate lengths. Incorrect identification usually results in identifying closely related genus or species rather than the actual one (Ward, Gilmore, Robertson, & Peakall, 2009). Use of proper controls can help avoid this problem. This can be done by using all target species; with unrealistic inclusion of 10, 000 species, say for example if grass were to be used as evidence. DNA barcoding in plants presents challenge due to difficulty in finding a single variable barcoding gene in plants. This is because genes in mitochondrial DNA (used for barcoding) in plants evolve at a slower pace and show limited variations (Ward, Gilmore, Robertson, & Peakall, 2009). Hence a combination of morphological and molecular strategies is the solution for species identification tools in forensic botany. Importance of forensic botany to police investigation became very obvious in the O. J. Simpson trial in 1995. Testimony suggested that the murderers probably hid in the bushes near the Simpson’s house waiting for the victim. If this were true, pollen grains from the nearby flowers were bound to get on the perpetrator’s clothing by brushing against the plants. Only if this had been discovered, and noted by the police during the investigation, the trail would have taken a different turn. If the pollens were fingerprinted, the killers could have been put on the crime scene and establish Simposon’s innocence or guilt. He was acquitted in 1995, but found liable later in a civil court (Hunter, 2006). This case highlights the importance of botanical samples to be collected by police during investigations, be it a small case or a high profile murder case. All the above mentioned cases exemplify the potential for plant material to be collected as an important source of forensic evidence under certain circumstances by the police. A close collaboration between police and botanist can narrow down the case for police. “The greatest advancements in forensic science over the coming decades will not necessarily be in technology, but instead through enhanced administrative practices and better collaboration with other agencies in our criminal justice system” says the Michigan State Police. Professor Bock and Norris from university of Colorado are of the opinion that forensic botany is an under-utilized resource. They believe this is because of lack of botanical knowledge among most people involved in criminal investigations (Bock, & Norris, 1997). A survey in 1990 of 30 of the largest forensic laboratories in the USA found that only 2 knew that pollen could be used as a forensic tool (Bryant & Mildenhall, 1990). The value of botanical evidence has been clearly demonstrated and is accepted by the courts now; but lack of recognition of its value reflects to some degree the absence of botanical training in contemporary medical and allied health curriculum. It is time that academic institutions, for their part, must once more appreciate the value of providing well-rounded instruction in botany within their undergraduate biological programs (Bock, & Norris, 1997). Forensic botany is a valuable tool that deserves wider use. Reference List Asymmetry - The Future of Forensic Science. The Future of Forensic Science. Retirved from http://www.michigan.gov/textonly/0,2964,7-123-1593_3800-16019--,00.html Bock, J.H., Norris, D.O. (1997) Forensic botany: An underutilized resource. J Forensic Sci 42(3): 364-7. Bryant, V. M., & Mildenhall D.C. (2011). Forensic Palynology in the United States. Retrieved from http://www.crimeandclues.com/index.php/forensic-science-a-csi/trace-a-dna/24--palynology-in-the-united-states Bryant, V.M., Jones J. G., & Mildenhall D.C. (1990). Forensic palynology in the United States of America. Palynology 14:193-208. Carita, E. J. (2004). Forensic Botany Principles and Applications to Criminal Casework. New York: CRC Press. Erdtman, G., (1969). Handbook of Palynology. New York: Hafner Publishing Co. Et tu, Julius? (March 09, 2003). The London Sunday Times. Retrieved from http://www.forensic-psych.com/articles/artLTimesEtTuJulius3903.php Graham, S. A. (1997). Anatomy of the Lindbergh kidnapping. J Forensic Sci 42(3): 368-377. History of Forensic Science. Forensic Science Central. Retrieved from http://www.forensicsciencecentral.co.uk/history.shtml Hunter, Philip. (2006). All The Evidence. EMBO reports 7 (4): 352-354. Key Dates in the History of DNA Profiling. Crimtrac. Retrived from http://www.crimtrac.gov.au/our_services/KeyDatesintheHistoryofDNAProfiling.html Krause, B., Seifert, S., Panne, U., Kneipp, J., & Weidner, S.M. (2012). Matrix-assisted laser desorption/ionization mass spectrometric investigation of pollen and their classification by multivariate statistics. Rapid Commun Mass Spectro 26(9): 1032-8. Newman, C. (1984). Pollen: breath of life and sneezes. National Geographic Magazine, 166(4):. 490-521. Palenik, S. (1982). Microscopic trace evidence—the overlooked clue: Part II, Max Frei— Sherlock Holmes with a microscope. Microscope 30: 163-168. Timeline. DNA. Retrieved from http://www.dnai.org/timeline Ward, J., Gilmore, S.R., Robertson, J., & Peakall, R. (2009). A grass molecular identification system for forensic botany: a critical evaluation of the strengths and limitations. J Forensic Sci 54(6):1254-60. Read More