MOLECULAR TECHNIQUES FOR IDENTIFICATION
Q2. Critically evaluate the potential of DNA from plants specimens to inform investigations into illegal activities. Illustrate your answer in specific examples
The study of plant science and how it relates to criminal investigations is known as forensic botany. Forensic botany looks at different aspects related to plants and plant DNA. Some of the areas it looks at are dendrochronology which is the study of tree rings, palynology- study of pollens, limnology- study of the aquatic environment, ecology, systematics and molecular biology.
DNA is the main blueprint for genetic information in all living cells. It consists of four nucleotide bases namely Adenine(A), Cytosine(C), Guanine(G) and Thymine(T). A matches with T and G matches with C. These are chemically joined together to form a double helix structure which is known as DNA.
Plant DNA is still a developing aspect of forensic science; however, it has been used in several criminal cases and has led to convictions of the perpetrators.
Plant DNA can be used to determine if the scene of crime is primary or secondary, meaning they can enlighten the investigators on whether the crime took place in the area that they found their major evidence or if the location they are at was just used as a dumping location especially in cases involving dead victims. Some plant pollen last longer on clothing, especially clothes made of out cotton which means the investigating tam can test for the pollen 2 weeks later on the suspects clothing to try and link the suspect to the crime scene. In cases of drug dealing and distribution, the plant material that is recovered from the victim/ scene of crime and the suspect can be compared using validated scientific methods and if the STRs are identical, they can therefore be compared to the present database relating to the samples that were being investigated for further confirmation.
Identical genotypes are more likely to happen because the propagation that is used when growing the plants. Some people use the clonal propagation and not the sexual propagation. Clonal propagation is used by more by the people that grow and distribute drugs ie, marijuana because they prefer to keep their product quality the same throughout. Clonal propagation produces plants that have the same genetics. In addition to this, DNA typing in clonal propagation gives a direct linkage to the person who grows the marijuana or the most common distributor.
The plant evidence also depends on the type of crime that has been committed. There are several types of evidence that can be recovered for plant DNA and these are;
Leaves and other parts of plants that can be identified
The above stated types of evidence that can be recovered for plant DNA analysis can be used in different cases including;
Hit and runs
Sexual and physical assault
The plant evidence that is recovered for analysis ca be used to;
Link suspect to a crime scene
Person to person
Person to other types of evidence that has been recovered at the crime scene
Help identify missing persons
Link bodies to their primary and secondary locations of crime
Find the origin of the plants if it is drug related, find the origin that will lead you to the producer/ supplier or distributor
However, one must be careful when dealing with botanical of evidence because the presence of leaves or pollen on individuals always mean they were involved in the crime that is being investigated, they should always remember the Locards principle, every contact leaves a trace. This depends on the amount of evidence found on an individual, less can be disputed but more, it is difficult to argue that the individual was not near or at the scene of crime. Another consideration the investigating team must account for is that pollen can be difficult to link to a specific area because it is common.
Plant DNA can be used and recovered from varies things for analysis to solve the crime committed, for example, in a sexual and physical assault case, the grass stains can be analysed and matched to the grass where the incident took place.
In cases where there are 2 locations involved, primary and secondary location, if there was a car involved, evidence can be found on the wheel wells, under the car mat, vehicle trunk and the vehicle undercarriage. In addition to this, when recovering plant evidence, it should be correctly packaged and labelled. If there are 5 samples collected in one location but different parts of the location, this should be specified and labelled on the evidence packages as this can help when reconstructing the events of the crime committed.
Plant DNA typing has four considerations, namely;
The four considerations determine whether there should be further testing of the plant material recovered or if the can be an interpretable DNA profile from the recovered plan evidence. In addition to this, the size of the plant fragment and the analysts ability to break the plant cell wall mechanically to enable sufficient DNA content release should be considered.
CASES SOLVED USING PLANT DNA( FORENSIC BOTANY)
THE HOEPLINGER CASE
May 7th 1982, John Hoeplinger killed his wife Eileen Hoeplinger and claimed that she was killed by an intruder, he later changed his story after he was confronted with botanical evidence saying that he had an argument with his wife and went he went to apologise to the wife, he found his wife on the driveway, however he continued to say there was an intruder who committed this terrible crime. The botanical evidence that lead to him being caught was the algae that was on the shirt that he had told the investigators that it belonged to him. The algae on his clothes matched the algae in the pond water that the murder weapon was disposed. He got the algae on his shirt when he was disposing the murder weapon. The microscopical organisms found on Joe Hoeplingers t-shirt was linked to the murder weapon and he was convicted for his wifes murder.
LINK A BODY TO A SUSPECT- KIDNAPPING CASE
Sydney, Australia, July 7th, 1960, a young boy disappeared while making his way to school and his parents later received a call demanding ransom money, ?25000 for him to be set free, alive and safe. His body was later found about 10miles from his home. He had been beaten and oxygen deprived. There was mould growing in his shoes and socks because his body had been wrapped in a rug. Further botanical evidence that was found on his body was the leaves, twigs a pink, substance that was crusty and seeds. The botanical evidence was analysed, and the fungi was determined to be made up of different composition and it had started growing just after the boy was kidnapped. The seed was not from a common tree and was not a tree that was anywhere near where the body had been discovered which made it easy to narrow down the location. The pink substance was a building material that was used in house facings. The police put out a word in the streets asking for help and luckily for them, one postal worker came forward and gave them a location that was near the tree that produced the seeds that were collected and analysed from the boys body and the house that had the pink, crusty material. On arrival at the house, the suspect was nowhere to be found, he had left with his family. Alongside the botanical evidence that was collected and analysed, there was other forensic evidence that matched the description of the information that the neighbours gave the police. Istvan Baranyay was arrested and was charged for the crime on March 29, 1961.
THE WOOD CHIPPER CASE: LINKAGE OF A VEHICLE TO A CRIME SENE THROUGH WOOD FRAGMENTS
Richard Crafts killed his wife Helle Crafts and told the police that Helle had gone to look after her unwell mother in Denmark. However, Richards story begun to fall apart when friends and neighbours started talking because they were concerned about Helle disappearance. Richard had said Helle had gone down to Denmark but she had not taken any clothes with her which is unusual. Her mother was called to ask if Helle was at hers and the mother had no idea where her daughter was, and she was in perfect health therefore there was no reason for Helle to go down and look after her. Looking into Richards recent activities, they revealed that he had recently bought a chainsaw and a Westinghouse chest freezer, rented a hook to tow heavy equipment and he had reserved a Badger Brush Bandit wood chipper. Days later, a snowplow driver reported that there was a wood chipper on the road side by the Housatonic river and this stopped him from completing his route. The investigators went to the place where the wood chipper was reported to be, and they collected physical evidence that was later used to convict Richard Craft for murdering his wife. The plant evidence that was recovered for analysis and the bone fragments were of importance in in this case. The wood chips collected from the riverbank and from the truck that Richard had rented had identical cut pattern which matched the wood chipper cuts.
A body of an unknown woman was found in Arizona desert and next to the lifeless body was a beeper that led the investigators to the owner of the beeper, Mark Bogan. Mark Bogan had a truck and in the truck, there were seed pods of the paloverde tree which is the tree that was on top of the womans body. The seed pods from the scene of crime and the seed pods recovered from the truck were analysed and compared and they were found to be a match. Mark Bogan was convicted for the murder of the woman.
OF LEAVES AND MEN: THE IDENTIFICATION OF A BODY THROUGH LEAF LITTER COMPOSITION-
CASE OF A MISSING CHILD
California Department of Justices two criminalists phoned up the Department of Botanical Sciences- California State University in Chico asking for help because they had no idea on how to proceed with solving the case. The childs father was found dead, he had committed suicide, gunshot in Bute County, CA. The evidence that was collected was plant material that was found in the truck and the leaves that were collected from the missing childs clothing that was also found in the truck. There was blood all over the clothing and the leave evidence that was collected. The leaves collected varied from fully decomposed and partially decomposed and this led the botanists to believe that the samples where from the top of the litter composition. There were different types of leaves that were found within the leave composition and there were some fresh leaves of the arctostaphlos patula which is a Greenleaf manzanita, quercus chrysolepis which is a canyon live oak, abies concolor(white fir) and quercus kelloggii which is a black ok. Preliminary analysis were carried out on the samples and they reference samples was used for comparison. Each individual leaf that was recovered was then analysed for the arrangement of its vein characteristics, general appearance and leaf margin. It was not possible to positively identify the oak species; however, they were either interior live oak or canyon oak and these results were based on the dried leaves samples. Locations for the missing childs body were eliminated based on the known species distribution. The different species that were observed did not match Nevada or eastern Sierra Nevada therefore these places were ruled out, rather, the live oak shown that the recovered sample was most likely to have come from the western Sierra Nevada. The common leaves that were recovered were the white fir and the live oak which indicated that the place had the sources of these leaves or it was a nearby a place that has the sources of the leaves recovered. Due to this, a conclusion was reached that the dumping site was less likely to be north or east facing slope because of the live oak being present and it could not be a south facing slope because of the white fir being part of the leaves recovered. This left one direction left, the west facing slope that had moist environment. The leave content that was recovered was dark in colour which meant that the dumping site had a high organic content which then aided the conclusion that the body was in a site that had a fairly dense forest canopy. There had to be some source of light in the area and this was shown by the presence of the Greenleaf manzanita.
A location for the body site was started on the 5th June 2002 around the area the truck was found and that is when a match of the leaves that were recovered for analysis was noted. The fairly dense forest canopy, white fir and Greenleaf manzanita were seen, and this was the area of interest that had to be searched further. The detective took some location readings using the Geographic Positioning System. And after searching 4 sites, the fifth site matched the description that was given by the botanical analysts which was not far from where the truck was found. There was a strong decayed odour at this location which led the detective to finding the body of the young girl under a blanket.
Plant DNA plays an important role in criminal investigations, there are cases were there was not enough forensic evidence to convict the perpetrator and because of botanica evidence the cases were solved. Same as other forensic evidence collected at scenes of crime, botanical evidence should be collected accordingly, packaged and labelled correctly. It should also be photographed and described in details; width, length, colour, texture and other descriptions that will be seen. The appropriate personal protective clothing should also be worn when dealing with evidence as some of the plant species can be poisonous. If the evidence is not handled correctly and not analysed accordingly, it will be deemed inadmissible in court which will lead to the case being thrown out of court and the perpetrators getting away with the criminal act they have committed. Accurately recording the scene of crime and providing detailed documentation of the scene of crime alongside detailed and descriptive evidence recovered is the major key factor in having a successful case.
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