Forensic Botany PDF

Forensic botany  Definition: Forensic botany is the applied scientific discipline that regards the general study of botanical evidence in judicial investigations and includes many sub-disciplines, such as palynology (the study of polllen and spores), dendrochronology (the study of growth...

Forensic botany  Definition: Forensic botany is the applied scientific discipline that regards the general study of botanical evidence in judicial investigations and includes many sub-disciplines, such as palynology (the study of polllen and spores), dendrochronology (the study of growth rings of tree stems and roots), lichenology (the study of lichens), mycology (the analysis and the identification of fungi) and bryology (the study of bryophytes). Plants as evidence identification of the plant is an important first step. A plant’s name is the key that opens the door to all the known information about any particular plant. Is it poisonous to humans or livestock? Can it be eaten? How big will it grow? Where should it be planted? Is it a weed? Many, if not most, crime scene personnel have a very difficult time finding plant evidence. Often, investigators do not see a plant because they do not recognize the object as a plant. Recognition of the various common groups of plants is necessary to be able to find and utilize plants in forensic investigations. Types of plants Vascular plants Vascular plants are those that have a transport system to conduct water and food throughout the plant. a. Seedless plants Ferns are a group of vascular plants that reproduce via spores and have neither seed nor flowers Ferns b. Seed plants 1. Cycads 2. Conifers 3. Flowering plants a. Monocot b. Dicot Non-vascular plants algae moss Non- plant traditionally studied by botanist Fungi Lichens Basic plant characteristics for the forensic investigator The following characteristics should be learned to provide a background for recognizing the different kinds of plant evidence at a scene. Habit In botany, a habit can be described as the tendency of a plant to grow a certain way. One major habit is that plants can be primarily woody or herbaceous (not woody). a. Woody plants Woody plants are perennials that produce secondary growth in the form of wood. they are usually classified as trees or shrubs. b. Herbaceous plants Herbaceous plants are those that lack a persistent woody stem. Woody plant Herbaceous plants Stems Stems are defined by having a bud in the axil of a branch. Stem shapes can be round or square. A rounded stem is the most common stem shape. However, the investigator should not assume that all stems are round. A detailed inspection should be made and supplemental photographs taken to aid in identification. Leaves A leaf is an above-ground plant organ specialized for the process of photosynthesis. All crime scene personnel should be able to generally categorize leaves that appear different. The basic characteristics useful for separating different plants based on leaves are described and shown below. Leaf arrangement Leaf arrangement on stems can be opposite, alternate, or whorled. Leaf types Simple Divided Leaf arrangement opposite whorled alternate Leaf types Divided leave Simple leave Leaf lobes The number of lobes on a blade is important for identification. Lobes can be regular or irregular Leaf tips The apex of a blade can be obtuse (rounded), acute (slightly pointed), acuminate (pointed). Leaf margins Margene of the leaf refers to its edge Leaf margins Leaf tips Leaf shapes Hairs Plant hairs (trichomes) frequently occur on various parts of the blades and stalks. Many kinds of hairs occur. More than one kind of hair can occur on the same part of a plant. Hairs may be simple with one cell, or branched. Hairs can be located on any part of the leaves or stems. Roots Roots are often an important aid in the identification of a plant, but since roots are usually located below the soil surface they go unnoticed and underutilized by legal investigators. Flowers Flowers are one of the primary means by which plants are identified. Flowers are commonly composed of sepals, petals, stamens, and pistils. Fruits A fruit is a ripened ovary that provides the plant with the means for reproduction. Visualization and identification of such small objects requires careful examination, often with magnification. A hand magnifying lens or a loupe is an excellent tool for the scene investigator. On collecting any plant evidence, the two most Botanical evidence in legal investigations To be of value, plant evidence must first be interpreted by a botanist. Typically, legal investigators should seek a botanist with well-rounded training and experience who possesses knowledge of the various specialties within the botanical field in question Some of the various botanical specialties involve systematics (plant names), anatomy (plant cells), morphology (plant structures), ecology (relationship of organisms within the environment), and physiology, chemistry, and genetics (DNA). Alibis In many criminal events, an alibi can prove to be useful. Fortunately, very few individuals who are not botanists can successfully lie about plant evidence. Because plants grow in specific areas, an object or person can often be linked to that location by plant evidence. Plant pieces found underneath a vehicle or on clothing can be linked to the location of the crime Plant evidence can also show where the person or vehicle had previously been. Timing If a woody plant with seasonal growth producing annual tree rings is found growing on a grave or growing through a skeleton, the annual rings can be counted. The number of rings, corresponding to a year per ring, can show that the grave or skeleton was at this location for at least that many years. The difference between the shades of yellow and the natural shade of green can be determined by burying many replications of the same plant parts at the scene and uncovering them at predetermined intervals. When the experimentally buried plant color matches that collected at the crime scene, it can roughly determine when the plant part was buried. The amount of wilt (to become weak and begin to bend towards the ground)present on broken or damaged leaves and branches can help to establish a time frame. Chlorophyll degradation of plant leaf from a burial site can be used for time interval estimations.  A moss growing on human bone can useful for determining a portion of the postmortem interval Plate Gravesite growth A common fallacy is that the vigorous growth of plants on and around a gravesite or body is due to the nutrition provided by the deterioration of the body. In the early postmortem period this is simply not true. because, a body placed on plants will keep sunlight from reaching the plant, causing most plants to die due to a lack of photosynthesis. Most stems and root systems would eventually die because of the caustic fluids and lack of photosynthesis. The easily observed vigorous plant regrowth over and around a gravesite is due to the disturbance of the soil, not any nutrition provided by the remains. The soil disturbance exposes seeds in the soil to environmental factors that will trigger growth. Stomach contents Plants within stomachs or feces can be identified by means of their anatomy. Sometimes the contents can lead investigators to the place of a last meal. Ingestion and partial digestion of a poisonous plant could also be determined. In some regions of the world plant poisoning is more frequent. Evidence collection and analysis Botanical evidence is most often preserved by simply pressing plant material and allowing it to dry naturally. This is because plants retain nearly all of their morphological characteristics after drying. Although the colors and shapes of the fleshy parts of plants, such as fruits, often change, these characteristics can be noted and recorded when they are collected. Photography is an excellent method to use for the documentation of the physical characteristics observed at the crime scene before the collection drying process begins.  Fresh plant material contains moisture and sugars. Both of these elements promote the growth of bacteria and fungi, and the higher the sugar and/or moisture content, the faster the decomposition and degradation of the sample. If heat is also present, complete decomposition of the plant sample can occur within 2–3 days, with many of the distinguishing characteristics disappearing within a few hours. To help prevent plant decomposition and sample degradation, it is crucial to not collect plant material in plastic bags or any non-porous container. However, if plant material is stuck to a body part or soaked in fluids it may be collected in plastic and refrigerated until it can be safely dried. Coolers with ice or chemical ice (cooling packs) can be used for temporary storage in the field. However, the plant material should not be placed directly on the ice to avoid freezing and damaging the sample. If botanical evidence is allowed to freeze, the plant cells could become damaged and then quickly disintegrate, thereby destroying important identification characteristics. Any plant evidence in plastic bags should be placed in a refrigerator as soon as is practicable and examined quickly thereafter.  The whole plant, including roots, should be removed from the ground with a hand trowel , the soil should be gently separated from the root system and the plant specimen placed in paper. If the plant is too large for the paper or container it can be folded, zigzag or accordion style. If the plant cannot be folded, it can be cut in half or into sections. Each cut section can be put into separate paper and all sections of the same plant should have the same evidence number.. For extremely large plants, only a portion of the plant needs to be collected For instance a 20–30 cm portion of a branch or vine, with its accompanying leaves, should be satisfactory for identification.. Several samples of the same plant can be extremely helpful in determining the variation that exists. Be certain to look for flowers and fruits, and collect several samples of each.  Very small plant fragments or seeds can be put into a packet made from a folded piece of paper, called a druggist fold. Alternatively, thick roots, branches, stems, and bark can sometimes be split so that they conveniently fit into collection paper or boxes. Succulent plants, or samples with watery or juicy fruits such as an orange, should either be sliced thinly enough to place into newsprint or placed whole into a pasteboard box. Since sugar-filled fruits and excessively wet samples will stick to newsprint, such samples should have waxed paper placed on both sides or around them. This will keep the sample from sticking to the paper or cardboard container and still permit proper drying. If plant material becomes stuck to the paper or cardboard container, determination and analysis may be impossible.  A plant press is the best device to preserve and flatten plant evidence and facilitate the drying process. A plant press has a hard-wooden board on each side and is filled with successive layers of cardboard and newsprint (containing the sample), with blotter paper on each side of the newsprint. The blotters on each side of the newsprint will aid in removing the moisture and helping to dry the plant so that it will not deteriorate. Initial crime scene natation When doing the initial walk-through of a crime scene containing botanical evidence, there should be a review to determine if the plant material present may show how the suspect, victim, or vehicle entered and exited the area. Walking, physically carrying a body, or the use of a vehicle will cause damage to vegetation around or leading into the scene. It is important to remember that all plants at a crime scene, indoors or outdoors, may be valuable evidence, therefore the entire area should be carefully photographed before any evidence is processed. Photographs of the scene should show suspected route of access to the site. In addition to photography, In general, the method of collection should be as follows: (i) collect any evidence ofthe suspect’s pathway leading to and from the scene, (ii) collect evidence from the perimeter, especially plants typical of the surrounding habitat, and (iii) carefully search to find any remaining evidence throughout the scene Where to search for evidence Clothing and hair are obvious places to search for evidence, but everything exposed to plant material should be carefully examined, including pockets, cuffs, and textile seams, shoelaces and shoe seams. When dealing with vehicles as evidence, always search for plant material in the undercarriage and wheel wells. Small plants and fragments can often stick to wet smooth surfaces and can be found on any portion of an automobile. Plant seeds that have become attached to a sock fragments that have become attached to the undercarriage of an automobile  Bruised or broken plants can also leak sap, which can enable plant parts to stick to various surfaces. The spines and thorns found on many plants can pierce skin, clothing, and other substances. Also, there are many kinds of hairs found on plants, and these enable plant pieces to adhere to clothing and other surfaces. Most suspects overlook plant evidence because they have no knowledge of its possible importance. If warranted, to reduce the chances of missed plant evidence, have a botanist recheck all clothing and other evidence because trained eyes are more likely to see small pieces of plants. Any plant part touching or buried with human remains can be valuable evidence.Frequently the time of death, or prior locations can be indicated from plant material. When someone digs a hole to bury remains, they usually disturb and damage the associated plants to some extent. Soil from the hole is usually returned to cover the Subsequent raking or shoveling the excavated soil into the hole will damage additional plants around the burial. Photograph all disturbed areas around the hole carefully  Perennial plants such as trees, which grow for several to many years, often contain seasonal and/or annual rings. If a plant with annual rings is growing over, though, or closely adjacent to a body, skeletal remains, a gravesite, or object at a crime scene, the rings can be counted and provide a time interval. To collect a tree in order to preserve the rings or other significant damage, the tree and any damage to it should be carefully photographed. If the tree is too large to collect entirety, the trunk should be cut off a few inches below and above any damage. This section should be kept in a cardboard box in the same way as for any other larger plant evidence. Samples of the leaves or other vegetation should be preserved separately, but tied together by the same item/sample number.  The etching of bone by roots is a common occurrence in cases of extended time period burials. The depth of etching may be helpful in determining time intervals, but no research has been produced which shows the time interval necessary for the roots of various species of plants to etch bones. storage Plant evidence should be stored in a cool dry area. Plants are biological organisms and need to be killed and dried for the best preservation. each sample should be separated until dry. Drying will kill the plant and stop its biological processes. Drying is best if the plants are kept flat with cardboard and/or blotter paper on both sides and a weight placed on top. Fungi and other large plants or plant parts collected in cardboard boxes should be left in the boxes. Most plants kept in this manner will dry in 3–7 days if humidity is low. The samples should be kept in numerical order for ease of processing. The box should have a few mothballs or a pest strip included to repel any insects that may eat dried plants. Documentation of botanical evidence Environmental conditions are frequently overlooked and not recorded, but should always be noted: is the weather sunny/clear/partly cloudy/rainy (how much rain), is there a slight breeze, is it breezy or windy, what is the humidity, and what is the temperature? Habitat: The particular habitat (place) at the scene. The scene may be in a forest, but the sample may have been in an opening, ditch, or trail. Scene location: Usually only one scene location and description is needed and can be listed at the beginning of a log sheet. The scene must be linked to a permanent structure, such as a corner of a building, a utility pole (poles usually have an identification number), or a corner of a roadway. description of the location should always be made, although easily available geographic positioning systems (GPS) are common and can be used to provide a second confirmation of the location. Evidence location: Where was this evidence collected at the scene: on the body or vehicle, or elsewhere? Where on the body or vehicle was it found? If not on a body or vehicle, the evidence will require exact measurements for its location. Collector: Who actually collected the evidence? It is best if only one individual collects all of the plant evidence as chain of custody is vitally important. Each person who handles any evidence must be documented by a chain of evidence log. Agency: The agency and title of the plant collector must be noted. Date: The date of collection must be included in the log. Item number: Each plant sample must have a unique number. Time of collection: Note the time when each sample was collected. Type of plant: (if known): tree, shrub, herbaceous. Height of plant: (if known, and the entire plant is not collected): This measurement does not need to be exact, simply an estimate. Flower color: Color is often subject to change on drying. Fruit color: Color is often subject to change on drying. Fruit shape: Shape is subject to change on drying. Frequency: Look around to determine how common your plant is: common, frequent, infrequent, occasional, rare (only one seen). Botany field data sheet Case number:__________________________________________Date:______________________ Agency:_________________________________________________________________________ Investigator: ____________________________________________________________________ Scene location: __________________________________________________________________ Description of the scene:__________________________________________________________ Habitat assessment Description of habitat Describe: Obvious path, trail, or road to/through scene:______________________________________________ Broken branches:_____________________________________________________________________ Other obvious habitat disturbance(s):______________________________________________ Habitat sampling procedure Include list of trees, shrubs, ground cover, and herbaceous plant sescription of biological conditions at scene Item Description Location Disposition Visible botanical evidence description Describe: Plant material covering body, vehicle, or other object:__________________________________ Other plant evidence on body, vehicle or other object:__________________________________ Plant evidence under or buried with body, vehicle, or other object:________________________ Sampling procedure for botanical evidence Include list of botanical evidence collected Item Description Location Disposition Evidence transportation From Name/signature Date TO Name/signature From Name/signature TO Name/signature Evidence storage Include list of items of evidence being stored Item Description Location Disposition Evidence analysis Name of botanical analyst: Location of analysis: Conclusion:__________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________ How to have botanical evidence analyzed Local botanists are frequently very good at identification of the plants in their area using only vegetation, even fragments of vegetation, but a botanist from a different area may not be able to identify the plants easily If the local botanist is reluctant or has problems with procedures for case analysis, help can be quickly obtained by a phone call to an experienced colleague. Evidence analysis Evidence analysis can require special equipment such as a scanning electron microscope or other optical scopes, chemicals, trips to a scene, special collection techniques, unusual preparation for analysis, or additional information on different methodologies. Transportation of botanical evidence The chain of custody ensures that the evidence is secured and in someone’s possession or control at all times. A log sheet for possession of the evidence is kept with the evidence.The person who collects the evidence must keep the evidence in his or her possession in a secure place, usually somewhere with a lock. If the evidence is given to someone else it must be someone who is authorized to accept it, such as the keeper of a locked evidence storage unit or the director of a laboratory. Laboratory report A laboratory examination form should be compiled for each container. The form should list the date, case number, agency or company, contact person, method of contact, method of transport, and type of packaging. The form should document the kind of container, the date opened, and how the evidence was contained after opening. If several samples are in the same container they can be described separately on the same form. Care must be taken that each sample has a separate number. If a leaf or stem fragment is examined and a species cannot be determined, a simple note that the fragment is from a dicotoledyonous (dicot) plant or an unknown woody plant might suffice Botany laboratory examination data format Date: _______________________________________________________________ Case number:________________________________________________________ Agency (or company): _________________________________________________ Contact person:_______________________________________________________ Method of contact (phone, personal visit, etc.):____________________________ Method of transport (FedEx, US Mail, in person, etc.):_____________________ Type of packaging (box, paper bags, truck load, plastic bag, etc.):__________________ Information documented for each container: 1. What kind of container? 2. Date opened. 3. How is evidence contained after opening? 4. Contents of container. a. Number of samples. b. ID of samples or best description of each item if not able to ID. 5. Number of each identified (or unidentified) item per container. 6. Analysis. a. Method of analysis (dissecting scope, microscope, hand lens, b. Preparation details, if sample needs to be cut, stained, or otherwise prepared for analysis – should be noted step by step Step wise method for collection of botanical evidence 1. Set up field or botanical press a. Newsprint or other cheap absorbent paper should be folded over each sample. b. Each piece of evidence should have a case number and a distinct evidence number. Any writing, including numbering, should be done with a pencil or indelible marker containing ink that will not run or blot under moist conditions. c. Use wax paper to collect wet samples, such as those in watery or fleshy fruits, so that they will not stick to the paper while drying. d. Paper grocery-type bags and cardboard boxes can be used for larger samples or for cones or nuts that will not press flat. 2. Collection of plant material around and in the scene should include at least 10–12 samples of different plants around the scene a. Prune 20–30 cm samples of branches of woody plants. b. Dig up herbaceous plants and include roots. c. If the sample is longer than the press or box, fold each specimen in an accordion zigzag-like manner. d. If evidence is put into a paper bag, if possible the bag should be kept flat, just as for a sample put into a press. The flattened plant is more easily stored and less likely to incur damage by crushing of the dried material. 3. Each item of evidence should be photographed before it is collected and photographed again as it is placed into the press, bag, or box. The photograph of the plant being placed into the press, bag, or box should show the evidence number adjacent to the sample. Thank you