Fingerprints and Impressions Questions and Answers

Answer: C

The key names Galton as the father of fingerprint science.

Sir Francis Galton's Finger Prints (1892) gave the first scientific study of fingerprints: he showed that they are individual and persist unchanged through life, and described the minutiae (ridge characteristics) still used today. For this he is widely called the father of fingerprint science.

William Herschel used fingerprints for identification in Bengal earlier, and Edward Henry devised the classification system adopted by Scotland Yard, but neither established the science as Galton did. Edmond Locard is known for the exchange principle.

Answer: C

Fingerprint patterns may be damaged permanently in leprosy.

Leprosy damages the nerves, and the resulting loss of sensation, ulceration and atrophy of the skin of the fingers can destroy the ridges for good, so that prints cannot be recovered.

Eczema, scabies and superficial scalds affect only the outer epidermis; once the skin heals, the ridges grow back with the same pattern because the dermal papillae are intact. Only damage reaching the dermis, as in leprosy or deep burns, is permanent.

Answer: C

To obtain maximum detail, oblique light should always be used.

A three-dimensional impression in soil, snow or sand shows its detail through relief. Light from a low angle, at the side, casts shadows in the depressions and highlights the ridges, bringing out tread pattern, wear and damage. Photographers take several shots with the light from different directions.

Flat lighting or a flash directly above fills the shadows and flattens the detail. Ultraviolet light is for fluorescent traces, not for showing relief.

Answer: C

It is a multi-instances biometric system.

In multibiometrics, a multi-instance system uses several instances of the same trait, such as the left and right irises or several fingers, captured with the same kind of sensor.

A multi-sample system takes several samples of the same instance (several images of one iris), a multi-sensor system captures one trait with different sensors, and a multi-representation (multi-algorithm) system processes the same data with different feature extraction methods.

Answer: B

The pattern is a lateral pocket loop.

Both the lateral pocket loop and the twin loop are composites of two loops. In the Henry system, they are told apart by where the ridges of the loops exit: in a lateral pocket loop, the ridges traced from the cores emerge on the same side of the digit; in a twin loop they emerge on opposite sides.

A central pocket loop is a single loop with a whorl-like core, and an accidental is a pattern that combines two different types or fits no other class.

Answer: B

The epidermal ridges develop during the 3rd and 4th intrauterine month.

Volar pads appear on the fingers and palms of the fetus around the seventh to tenth week. As they regress, the friction ridges form, beginning around the tenth week and fully developed by about the 16th to 17th week, that is, during the third and fourth months. After that the pattern stays the same for life, growing only in size.

By the 7th to 9th months the ridges are long complete, and in the first month there are no ridges at all.

Answer: D

The material not used for lifting tool marks is sulphur.

Tool marks left on a surface are usually reproduced by casting or lifting. Wood's metal (a low-melting bismuth alloy) and dental stone are standard casting materials for them, and silicone casting compounds are used for fine marks. Cellulose acetate softened with acetone is used to take a replica of a mark on a hard surface.

Molten sulphur is associated with another job, casting footwear impressions in snow, and its casts are brittle. That is why it is the odd one out here.

What could not be confirmed: the cellulose acetate technique was found in only one source, so the answer relies mainly on sulphur's recognised use being elsewhere.

Answer: D

Imperfections on the surfaces are not class characteristics of tool marks.

Class characteristics are features shared by a group of tools of the same type, such as the shape and size of the mark and the direction in which the tool moved. They narrow the tool down to a kind.

Imperfections on the working surface of the tool, nicks, burrs and wear marks produced in manufacture and use, are unique to that one tool. They are individual characteristics, which allow a mark to be matched to a particular tool.

Answer: A

Indentations are three-dimensional contact patterns.

An indentation, such as a shoe or tyre mark in soil, or a tool mark in a door frame, is pressed into a soft surface and has depth as well as length and width. It is recorded by casting and oblique-light photography.

A two-dimensional pattern is a print left on a hard surface by transfer of material, such as a dusty shoeprint on a floor. 'Single-dimensional' contact patterns do not exist, and indentations are by definition three-dimensional, not 'mostly two-dimensional'.

Answer: C

The temporal parameters are (iii), (iv), (v): step time, stance duration and the swing/stance ratio.

Gait parameters are divided into spatial ones, which are distances and angles measured on the ground, and temporal ones, which are measures of time. Step time, the duration of the stance phase and the ratio of swing time to stance time are all timings of the gait cycle.

Step or stride width, foot angle and the gait line are spatial parameters, read from the positions of the footprints. Every other option includes at least one of them.