Fiber Examination In Forensic Science

INTRODUCTION TO FIBER

Fibers are long chains of molecule which are blended closely to form a string like structure and possess high tensile strength and high modulus. These characteristics can be attributed to the strong intermolecular forces like hydrogen bonding. These strong forces also lead to close packing of chains and thus impart crystalline nature. The fibers are then spun into yarns. These yarns are further knitted into fabrics. There are mainly two types of fibers:-

Animal fiber

It is also called as nature fiber. It is obtained from biotic sources like animals or plants. For example- cotton, wool, jute, silk, etc.

• Cotton- It is obtained from cotton plant. It is one of the most preferable fibers used in the textile industry due to its properties like long durability, smooth texture and is also good moisture absorbent.
• Wool- It is obtained from the hair of sheep. It is one of the most common fibers in the textile industry. It is a poor conductor of heat and therefore provides warmth during winters. It is used to make woolen garments.
• Jute- It is obtained from the jute plant and is commonly known as the golden fiber. It has high strength due to which it is preferred for making packaging material like bags or ropes.
• Silk- It is obtained from the cocoon of the silkworm. It is shiny in appearance. It is strong and used to make party wear clothes and sarees.

Synthetic fiber

It is also called as man-made or artificial fiber. It is a manipulated animal fiber which is blended according to the human needs. There are two types of synthetic fiber:

• Pure synthetic fiber
• These are entirely made of chemicals.

Examples –polyesters, nylon, etc.

• Polyester- These are the polycondensation products of dicarboxylic acids and diols. Dacron and terylene is the best known example of polyesters. It is manufactured by heating a mixture of ethylene glycol and terephthalic acid at 420 to 460K in the presence of zinc acetate- antimony trioxide catalyst as per the reaction. Dacron fibre (terylene) is crease resistance and is used in blending with cotton and wool fibres and also as glass reinforcing material in safety helmets, etc.
• Nylon- i. Nylon 6,6- It is prepared by the condensation polymerization of hexamethylenediamine with adipic acid under high pressure and high temperature(553K). It is used in making sheets, bristles for brushes and in textile industries. ii. Nylon 6- It is obtained by heating caprolactum with water at a high temperature. It is used for the manufacture of tyre cords, fabrics and ropes. Semi-synthetic fiber- These are prepared by taking natural polymers as their starting material and then add up the chemicals. Example – rayon.
• Rayon- It is a semi-synthetic fiber that man has created as a thought of producing silk chemically. It is made from cellulose found in plants which gives strength and structure to the fiber. Rayon can be prepared from the process of cuprammonium which uses waste papers as the raw material. It is prepared by converting cellulose into liquid form and later again into cellulose in the form of fiber. Cellulose is reacted with ammonia, copper sulphate and acid which produce viscose which is a soluble substance and can be converted into rayon.

Fiber as evidence

Fiber plays an important role in solving a criminal case. According to the Locard’s principle, “if there is contact between two items, there will be exchange of evidences” which means if there is any criminal activity happening around, no matter what the criminal will leave some evidence on the crime scene. Fiber unlike DNA cannot exactly help to find the criminal but can narrow the lane of finding the suspects.

Color me busted – Sometimes fiber can prove to be really strong evidence in some cases. In 1982, Columbus there was a girl named Kristen Harrison who was kidnapped and killed. At the crime scene the investigators found orange fiber evidence in her hair. With the analysis, it was found that it was polyester and had unique characteristics which were used in carpets. It was noticed that these fibers were similar to that of them found in a murder case of 11-year old victim prior to this case in the same locality. Initially, these orange unique fibers did not help in further investigation and all the hopes were lost.

After few months, a woman was kidnapped and held captive in his home. She was tortured and he had the plan to kill her later. On investigation, it was found that he drove the same van in which Kristen Harrison was abducted as seen by the witness and had same orange fiber as found earlier on the Kristen’s hair. Eventually, after a lot of investigations the owner of the van was convicted for the murder of the 11-year old girl, Kristen Harrison and the young woman. Therefore, it shows that fiber clearly plays an important role in solving a criminal case.

Fiber Compose and Exchange - While strands are vital bits of follow proof, we can't state that a particular fiber originated from a particular culprit or area. All things considered, fiber proof is viewed as fortuitous proof and reinforces any extra incidental or strong proof against a suspect.

At the point when two items come in contact amid the commission of a wrongdoing there is exchange of material starting with one individual then onto the next. Generally little texture strands are exchanged from the culprit to the person in question. This is immediate or essential exchange. On the off chance that a fiber is exchanged to an injured individual from the floor covering in an auto trunk or from a sweeping this is viewed as circuitous or optional exchange. It is additionally feasible for fiber materials to be exchanged from the unfortunate casualty to speculate attire yet this is a less regular wellspring of proof.

At the wrongdoing scene strands are gathered with tweezers or a gloved hand and set in small plastic evidence bag. The sacks are named properly and sent to the lab for examination. Strands found on the unfortunate casualties garments or hair are evacuated and sent for investigation in a comparative way. Filaments might be delegated Regular which incorporates, cotton, fleece, lama, alpaca, or different creatures. Characteristic filaments can likewise originate from plant materials like flax, hemp or kapok among others. A second rate class of filaments is man-made strands like nylon, polyester, rayon and acrylics.

Fiber Properties – Strands, regardless of whether from a floor covering, towel, or dress, all have certain physical attributes. These include: surface (smooth or rough), shading, crease (straight or wavy), malleability (flexible if twists, non-flexible if breaks), and strength (does it spring back when squashed or not). Various properties can be dictated by putting strands in or almost a fire. Does the material consume or dissolve? Does the fire turn shading? Does the material smoke on consuming? Provided that this is true, what does it possess a scent like? Be that as it may, in most snatching, assault or murder cases the measure of fiber material found is little. In these cases damaging testing like fire investigation isn't conceivable on account of the constrained material.

Microscopic Examination - Fiber proof is seen infinitesimally under various sorts of magnifying instruments. Notwithstanding consistent light or compound magnifying lens, the filaments are looked at under a stage differentiate magnifying instrument which permits a portion of the interior structure of the fiber to be uncovered. Hued filaments can be seen by fluorescence microscopy to recognize colors with fluorescent properties. Binds this to a brilliance spectrometer permits the assimilation (Shading) profile of the color to be created. Coordinating these profiles to known colors can distinguish the colors utilized and sometimes the particular color parcel number of a group of fiber. Survey the way in which color is adsorbed and connected along the length of a fiber may likewise give a prompt the way in which the strands were colored. Survey a cross segment of man influenced filaments to can, for a few strands, distinguish the producer of the fiber.

On the off chance that adequate fiber material is available some might be extricated by gas chromatography or other diagnostic strategies performed to decide colors, compound medications and even metals present in the fiber material. Examination of this to the fiber arrangement from a suspect can give solid supporting proof of the strands being from a similar source. Fiber information is produced by contrasting the shape, structure and size, color content, compound arrangement, and physical and minuscule appearance of two strands. In any case, in the last examination since two indistinguishable filaments can be coordinated it doesn't demonstrate that the strands are from a similar area nor does it demonstrate that the strands were exchanged to the unfortunate casualty at a similar period in time.

Method of microscopic examination-(a) SEM opened example chamber –Scanning electron microscopy (SEM) is strategy for photography which requires an instrument called the scanning electron microscope, which utilizes electrons as opposed to light to form a picture.

There are numerous focal points to utilizing the SEM rather than a light magnifying instrument. Utilizing SEM requires a huge profundity of field, which permits a lot of the example to be in center at one time. (b) Atomic force microscopy – Atomic force microscopy is a technique which is completed utilizing a nuclear power magnifying lens, or, in other words that can examine and portray tests at the minuscule level. The instrument enables the examiner to take a gander at surface qualities with extremely precise goals extending from 100 μm to 1 μm.

Fiber examination in forensic science Classification of evidence

Evidence can be delegated appeared in Coordinate proof incorporates firsthand perceptions, for example, observer records or police dashboard camcorders. Circumstantial evidence is an indirect proof that can be utilized to suggest a reality yet that does not straightforwardly demonstrate it. Nobody, other than the suspect and the victim really observes when circumstantial proof is left at the crime scene. Be that as it may, circumstantial evidence found at a crime scene may give a connection between the scene of crime scene and a suspect.

For instance, finding speculator’s firearm at the site of a shooting is conditional proof of the suspect’s presence at the scene. Circumstantial evidence can be either physical or biological in nature. Physical evidence incorporates impressions, for example, fingerprints, impressions, shoe prints, tire impressions, and instrument marks. Physical proof likewise incorporates filaments, weapons, slugs, and shell housings. Biological evidence incorporates body liquids, hair, plant parts, and normal filaments.

Most physical evidence, except for fingerprints, diminishes the quantity of suspects to a particular, littler gathering of people. Biological proof may make the gathering of suspects very small, or lessen it to a possible person, or, in other words in court. Trace evidence is a sort of circumstantial evidence, precedents of which incorporate hair found on a brush, fingerprints on a glass, soil traces into a house from shoes, and others. Fibers go under physical circumstantial evidence; all the more correctly it is trace evidence. Chemical examination of fiber-

Cotton

• Take a microscopic slide and add one or two strands of fiber onto the slide. Now, add 1% of sodium hydroxide solution to the slide and observe it under the microscope. If the fiber turns into violet untwisted or straightening of fiber with Turkish movement it will prove it to be the cotton fiber.
• Take a microscopic slide and add one or two strands of fiber onto the slide. Now, add 2-3 drops of cuprammonium solution to the slide and observe it under the microscope. If you see ballooning formation it will prove to be the cotton fiber.

Jute

• Take a microscopic slide and add one or two strands of fiber onto the slide. Now, add 2-3 drops of phloroglumicol solution and 1 drop of concentrated hydrogen chloride solution to the slide and observe it under the microscope. If the solution turns into a brick red color it will prove it to be the jute fiber.

Wool

• Take a microscopic slide and add one or two strands of fiber onto the slide.

Now, add 2-3 drops of lead acetate solution and slightly heat the solution with the temperature less than 55°C and observe it under the microscope. If the solution turns black it proves it to be wool. Express analysis Fiber logical front have seen a huge improvement which has had the best effect in fiber examination as of late because of the presentation of the diode exhibit spectrophotometer for inspecting and looking at fiber coloring. Because of these new instruments record over the whole ghostly range all the while, estimation just takes around 1 second, and therefore it is conceivable to screen many speculate strands from aggregates quickly. A group is a gathering of filaments of a specific conventional compose having a similar shading (ghastly example) and a similar morphology. The immediate aftereffect of this at some criminological labs has been to join unmistakable range diode exhibit small scale spectrophotometers, where optical properties of the strands can be seen under splendid field, spellbound and fluorescence enlightenment and the shading spectra recorded, utilizing just a single magnifying instrument. What's more, these instruments permit the likelihood for photograph documentation. A further outcome is the improvement of an online case convention framework, the data being input specifically at the work station. All data concerning case investigation is arranged to any of various terminals situated all through the fiber segment.

A concise portray the on-line convention might be-the cover sheet is the place every regulatory detail of the case are entered, and where the connections are discovered which prompt the pages worried about the fiber investigation and assessment. Extraordinary structures may likewise be incorporated for chronicle notes on material development and harm whenever required. All subtle elements of control and recouped filaments can be entered utilizing drop-down menus– for instance fiber compose, delusterant, coloring, fluorescence, cross area, liquefying point, optical properties and so forth. Extra data can likewise be included whenever wanted. At a later stage, by utilizing a pursuit routine it is conceivable to sort the recouped filaments into gatherings demonstrating similar qualities (for instance blue, delustered, shelled nut molded acrylic strands that fluoresce purple, yellow and orange under various channel blends). At this stage the spectra have not been considered. At long last, spectra recorded from potential matches among control and recovered strands can likewise be put away and looked at in the organized framework.

The product permits a selection of criteria which can be utilized as search parameters. It is conceivable to make otherworldly libraries and to look them for models of a specific range. For instance, the hits are recorded in a window on the privilege of the screen, with the best fit to the unearthly match being looked for being at the best. The connections coefficient is appeared in a second segment. An estimation of one would speak to a correct match. As the qualities fall, the level of incident with the desired range turns out to be less and less. Securing and retrieving evidenceIt is for the most part realized that the most generally rehearsed technique for recovering exchanged fibers is the utilization of adhesive tape however now it has been moved forward. The utilization of alleged "1:1 sequential taping", where the zone of one bit of tape speaks to the very same territory on the question being taped, was pioneered in Germany. It has the preferred standpoint that when managing a cadaver, it is conceivable to demonstrate that any exchanged strands found have been recovered from a very specific area. In the event that these fibers can be demonstrated not to start from the person in question or anything in his/her condition at that point there is a solid probability that they were saved by the suspect.

Such a finding may have two points of interest: it might give an investigative lead which can limit the selection of suspects; the example of fiber circulation may reproduce occasions amid the wrongdoing like choking, assault from the back and so forth. Due to such a large number of tape lifts, their assessment progresses toward becoming something of a calculated issue. Moreover, various conditions must be met, and even an accomplished evaluator must take care to abstain from giving data driving in the wrong heading. It has been recommended that a bargain in taping may give the best answer, where the body region is still subdivided into little regions, yet the aggregate number of recordings would be constrained to around 34. This would accelerate the entire procedure extensively, while as yet giving more intricate data than is accessible with standard taping. Aside from the examination of exchanged filaments, examination of materials, strings, ropes, string, bands, wicks and material tapes may likewise be included. All the time data about the development, completing and conceivable inception of a thing is asked. Such examinations require broad information of material completing and generation forms, yet can prompt a more extensive scope of uses for fiber investigation.

Due to such a large number of tape lifts, their assessment progresses toward becoming something of a calculated issue. Moreover, various conditions must be met, and even an accomplished evaluator must take care to abstain from giving data driving in the wrong heading. It has been recommended that a bargain in taping may give the best answer, where the body region is still subdivided into little regions, yet the aggregate number of recordings would be constrained to around 34. This would accelerate the entire procedure extensively, while as yet giving more intricate data than is accessible with standard taping. Aside from the examination of exchanged fibers, examination of materials, strings, ropes, string, bands, wicks and material tapes may likewise be included. All the time data about the development, completing and conceivable inception of a thing is asked. Such examinations require broad information of material completing and generation forms yet can prompt a more extensive scope of uses for fiber investigation. In future, it might wind up advantageous that such cases are analyzed in a territorial focus where extraordinary ability is accessible. The measurable science benefit in the UK has utilized fibers effectively to manage volume crime (auto burglary). They issued an extremely basic auto situate fiber taping unit and pre-printed data shape to nearby police. These are come back to the research facility and can be inspected quickly for strands prone to have begun from speculates garments, furnishing the police with a snappy and attractive result in around 70% of entries. In spite of the fact that not another thought in itself, this is an inventive method for putting fiber evidence to great utilize.

Conclusion

At whatever point two individuals come into contact with one another, a physical exchange happens. Hair, skin cells, attire filaments, dust, glass sections, flotsam and jetsam from a man's dress, cosmetics, or any number of various kinds of material can be exchanged starting with one individual then onto the next. To a measurable inspector, these exchanged materials comprise what is called trace evidence. It's exceptionally troublesome for the criminal to dodge or clean trace evidence as much of the time he/she may not know about it. Appropriate recovery and examination/utilization of these follow confirms by a legal researcher can send the criminal in the slammer. Continuation of this circumstance is exceptionally attractive and if the expanding conceivable outcomes for trade visits between staff utilized in different research center frameworks can be acknowledged, at that point in any event in the filaments territory, worldwide collaboration will demonstrate genuinely valuable. Further, the nature of researcher and framework can be improved by the worldwide coordination and preparing which will at last prompts a crime free world.