Forensic Fiber and Hair Analysis: Microscopy, Spectrophotometry, and Identification Techniques

What is the most commonly used animal fiber?

Wool

From which animal is wool primarily obtained?

Sheep and sometimes goats

How does wool fiber appear under a microscope?

Like a long cylinder with scales

Name two types of cloth made from wool.

Cashmere and flannel

What is the main source of silk?

The mulberry silk worm

How does silk fiber appear under a microscope?

As a thin, long, smooth and lustrous cylinder

What is the most widely used plant fiber?

Cotton

What do cotton fibers look like under a microscope?

Flattened, irregular, twisted ribbons

What process is used to treat cotton to make it smooth and lustrous?

Mercerization

From which plant is linen derived?

The flax plant

How does linen fiber appear under a microscope?

Like bamboo can, with jointed cells and split, tapered ends

What are jute and hemp commonly used for?

Making carpet backing, rope, twine, and sacks

What is rayon made from?

Cellulose

How do synthetic fibers typically appear under a microscope?

As smooth, lustrous cylinders with uniform thickness

What are some common synthetic fibers?

Nylon, Orlon, Dacron, and Lycra

What is asbestos used for?

Making fireproof materials and protective suits

What serious health issues can arise from asbestos exposure?

Asbestosis and Mesothelioma

What is hair primarily composed of?

Keratin

What are the three layers of a hair strand?

Medulla, cortex, and cuticle

What is the role of the dermal papilla in hair growth?

It provides nourishment and contains receptors for male hormones

What happens to hair follicles in individuals predisposed to hair loss?

They get progressively smaller and hairs become finer

What is the first step in identifying a fiber?

Determining its type

What were most fabrics made from in the past?

Wool, cotton, linen, or silk

What is the challenge in identifying synthetic fibres?

Manufacturers combine many fibres to create fabrics, making complete analysis difficult.

Which natural fibres have distinctive appearances detectable under a microscope?

Wool, cotton, and linen.

What is a key characteristic of wool under a microscope?

It has a pattern of surface scales.

What technique can identify synthetic fibres that are difficult to distinguish microscopically?

Infrared spectrophotometry.

How does infrared spectrophotometry work?

It measures how compounds absorb characteristic wavelengths of radiation.

What does the absorption spectrum indicate?

It shows parts of the spectrum that suffer the most absorption, known as absorption bands.

What is the purpose of a spectrophotometer in forensic analysis?

To detect and record the unique absorption pattern of a substance.

What is the first step in analyzing a substance using infrared spectrophotometry?

Mixing it with dry salt (sodium chloride) to form a disk.

Why is sodium chloride used in infrared spectrophotometry?

Because it is transparent to infrared rays.

What can a forensic scientist determine from the graph produced by a spectrophotometer?

The compounds present in the sample and their quantities.

What common tests help distinguish fabrics?

The burning test and chemical tests.

How can hair be used in forensic science?

For DNA analysis and traditional methods of hair analysis.

What preliminary examination can determine the value of DNA analysis on hair?

Checking if the hair has root material attached.

What information can microscope examination of hair provide?

Whether it is human or animal, which race (if human), and the part of the body it came from.

How is hair prepared for examination in a forensic laboratory?

It is dry mounted on a glass slide or cross-sectioned and mounted for viewing.

What is the significance of hair's growth and replacement in forensic investigations?

It allows for minute examination of clothing and articles for evidence.

What limitations exist with hair evidence in forensic science?

Identification cannot be made with certainty based on hair evidence alone.

What is the role of investigating officers in forensic analysis?

To conduct thorough and painstaking work at the crime scene.

What can the shape and appearance of the medulla indicate?

It can help in identifying the species of the hair sample.

What is the purpose of making impressions of cuticular scales?

For detailed study of hair characteristics.

What is a common characteristic of synthetic fibres?

They often have smooth surfaces, making them hard to distinguish.

What can the pattern of absorption bands serve as for a chemical substance?

A unique 'signature' for that substance.

What is the significance of comparing absorption signatures?

To identify the compounds in a sample by matching known signatures.

What can the edges and shape of a piece of cloth help determine?

They can assist in making a physical fit with clothing from a crime scene.

What type of analysis may be inconclusive or not useful for hair evidence?

DNA analysis.

What is the importance of examining the construction of a fabric?

It can help trace it back to a specific type of clothing or weave pattern.

Can hair evidence alone confirm a suspect's identity?

No, identification cannot be made with certainty on hair evidence alone.

What can hair evidence provide in a murder investigation?

Hair evidence can provide valuable corroborating evidence of guilt.

What was the 'Wigwam' murder?

A case in 1942 where the decomposed remains of Joan Peale Wolfe were found, leading to the conviction of August Sangreat.

What type of evidence was found on the weapon in the 'Wigwam' murder case?

Nine head hairs identical to the victim's hair were found on the weapon.

Who was convicted in the 'Wigwam' murder case?

August Sangreat, who was found guilty and executed.

When was one of the first scientific papers on hair published?

In France in 1857.

What did Professor John Glaister publish in 1931?

Hairs of Mammalia from the Medico-legal Aspect, a standard reference work.

What are the characteristics of hair that make it useful in forensic science?

Hair is virtually indestructible and remains identifiable even in advanced decomposition.

What information can a forensic scientist obtain from a single head hair?

Information about the race, sex, and age of its owner.

What was significant about the hair found on Mable Tattershaw's clothing?

It was identical to the head hair of Leonard Mills, the chief suspect.

What is a jigsaw fit in forensic investigation?

A match between torn edges of cloth found at a crime scene and on a suspect.

How can tiny fibers be transferred in a crime scene?

Fibers can be left behind or picked up by the criminal during contact.

What is the average growth rate of head hair?

About 2.5 mm per week.

What happens to hair after death?

Growth ceases, but hair may appear more prominent as the skin shrinks.

How can hair assist in cases of arsenic poisoning?

Hair absorbs poisons from the bloodstream, allowing for analysis of dosage.

What can the examination of hair roots indicate?

Whether hair has fallen out or been forcefully removed, indicating a struggle.

How can DNA analysis be used with hair evidence?

Standard DNA profiling can be used if root structure is present; mitochondrial DNA testing can be attempted with just the shaft.

What are fibers in the context of textile production?

Fibers are the basic unit of raw material suitable for conversion into yarns and fabrics.

What is a filament in terms of fibers?

A fiber of extreme length.

What types of fibers were commonly used in fabrics before synthetic fibers?

Wool, cotton, linen, and silk.

What tests can help distinguish fabrics?

The burning test and chemical tests.

Why is it difficult to analyze modern fabrics?

Manufacturers combine many fibers in making a single fabric.