Bosma expert witness

8/20/2019 Bosma expert witness

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D/Cst Rob FELSKE

Halton Police Service

Forensic Identification Services

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Halton Police-Forensic Identification Unit

• Scene Examination/Photography

• Fingerprints

• DNA

• Scene mapping and measurement

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Fingerprints

• Since 2012 I have compared over 35,000

fingerprints and Identified 211 individual

impressions.

• Teaching at the Ontario Police

College/Halton Police

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Friction Ridge Skin

• Friction skin is found on

the underside of your

hands and feet

• Evolutionary adaptation toallow gripping.

• Skin grows around

individual pore openingsto create a ridge unit.

Ridge units fuse together

to form ridges.



5Wertheim and Maceo, 2002

• Between 12-24 Weeks

– Ridges become visible spreading across fingers

– Convergence of the 3 fields at delta area

– The position of volar pad regression determines final pattern

12 weeks 24 weeks

Development Timeline for Friction Ridge Skin



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Arch Loop Whorl

Three Basic Pattern Types



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After comparison of 3,920 fingers of twins, no two fingers were

found to be the same.

Twin Study - Uniqueness

Lin et. al., 1982



Premises of Identification

Friction Ridges are developed on the fetusin their definitive form before birth;

Friction Ridges are permanent and neverchange except through scarring and

disease;

Friction Ridge formations are unique and

never repeated;

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Reliability of Fingerprints for

Identification

Used for identification since ancient times

Basis for the Identification of Criminals Act

AFIS searches millions of impressions

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Reliability of Fingerprints for

Identification

Every day AFIS (Automated Fingerprint

Identification System) continually searches

millions of fingerprints and no twofingerprints have ever been found to be the

same.

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Analysis

Comparison

Evaluation

Verification

ACE-V



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Analysis-Step #1



Methodology for Comparison

Scene impression analyzed to determinesuitability to compare

If the impression is too poor in quality it is

not compared to known prints

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How a fingerprint is analyzed

Substrate (the surface the print is on)

Matrix (the fingerprint substance)

Development Medium (process to develop)

Deposition Pressure (force used to deposit)

Lateral Pressure (slipping/twisting)

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Substrate

Substrate is the surface on which the

impression was deposited. Substrate can

cause distortion if the surface is textured,reflective, multi-coloured, dirty etc.

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Matrix

Matrix is the substance that is on the finger

and is eventually deposited onto the surface,

thus creating the fingerprint. In most casesthis is a combination of sweat and oil, but

can be other contaminants such as blood or

food grease etc.

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Development Medium

The development medium is the process or

chemical used to help enhance the

impression by making the impression visible.Development medium can range from white

light to dye stains that fluoresce the

impression at various wavelengths.

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Deposition Pressure

Deposition pressure refers to the amount ofpressure used when the finger makes

contact with a surface. The amount of

pressure used can dramatically change theway an impression looks after it is

deposited.

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Light Medium Heavy Extreme

Amount of pressure exerted when print is deposited

Deposition Pressure



Lateral Distortion (Movement)

Lateral Distortion refers to the movementthat occurs at the moment the finger makes

contact with the surface of the item being

touched.

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Anatomical Aspects

Anatomical aspects relate to the shape/patterns

present in the impression and takes into account

the most likely way an item was handled.

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Anatomical Aspects



Clarity

Clarity refers to the quality of the detail in theimpression.

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Levels of Friction Ridge Detail

• Level 1 - Overall

ridge flow

– Orientation

– Pattern Type

– Focal Points

• Core

• Deltas• Scars

• Creases

Identifications cannot occur at this level of information,

however exclusions can occur.



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• Level 2 - Ridge path

– Characteristics

• Type• Location

• Direction

• Spatial Relationship

– Continuous Ridges


Identifications and exclusions can occur at this level of

information.



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Ending Ridge Bifurcating Ridge Dot

Three Types of Level 2 Characteristics



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Level 2 Information - Ridge Paths

Continuous Ridges



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• Level 3

– Size and shape of

pores and ridges• Pores

• End shapes and angles

• Edge shapes

• Width

Identification and exclusion decisions can be supported at

this level of information.




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Knowledge

Experience

EducationTraining

Translation of Information

3 Dimensional 2 Dimensional



Transfer from 3 D ridge to 2 D print

When a 3 Dimensional ridge touches asurface it creates a 2 Dimensional

fingerprint.

The skin on the finger is pliable and moves

easily with pressure.

No two impressions are ever deposited

exactly the same way.30



Transfer from 3 D ridge to 2 D print

The Impression found at a scene can vary in itsappearance due to the innumerable ways the

finger can touch an object.

The amount of pressure (force) used to touch a

surface affects how the fingerprint will look (i.e.

thick vs thin ridges)

Twisting during touch can cause ridges to fold into

neighbouring ridges and distort the impression.

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Analysis

At the conclusion of the analysis stage, the

examiner must determine if the impression

is of value to proceed to the comparisonstage. If the impression is determined to be

of value, a comparison will occur. If the

impression is too poor in quality, the processwill stop at this stage.

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Comparison

Step #2

• It is at this stage that the unknown scene

impression is compared to the known

impression.

• The unknown impression is typically

compared to the known rolled or flatimpressions. Rolled impressions look

dramatically different than impressions

deposited during normal touching. 33



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Impressions taken from Dellen MILLARD

August 1, 2013



Comparison

The ridge formations located in the unknownimpression during the analysis stage are

searched for in the known impression.

If a ridge formation from the unknown

impression is not located in sequence in the

known impression, the process ends and theknown print is eliminated as the source.

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Comparison

.

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• Identification – “The determination of an examiner that there is sufficient quality

and quantity of detail in agreement and sequence to concludethat two friction ridge impressions originated from the samesource.”

• Exclusion – “The determination by an examiner that there is sufficient quality

and quantity of detail in disagreement to conclude that two areasof friction ridge impressions did not originate from the samesource.”

• Inconclusive – “During Evaluation, the conclusion reached that neither sufficient

agreement exists to individualize nor sufficient disagreementexists to exclude.”

SWGFAST Glossary (5/8/09 ver 2.0)

Three Conclusions in Evaluation



Evaluation

At the Evaluation stage, the examiner mustanswer two questions.

1. Is there agreement, in sequence,

between the unknown and known

impression?

1. Is there sufficient uniqueness to

individualize?38



Present Case

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Analysis of R1143-1

Substrate Distortion

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Substrate

Distortion

The substrate in this

case is a rear view

mirror. The mirror

causes a blurring

effect due to the

reflective nature of the

mirror.

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Matrix

Distortion

In this case

there is no

matrix, as theridges took dirt

away from the

surface.

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Development

Medium

The developmentMedium used is

Rhodamine 6G Dye

Stain after Cyanoacrylate

(superglue). There is nomajor Development

Medium distortion. The

dye viewed at 532 NM

with an orange filter

causes the yellow

appearance.44



Deposition

Pressure

The ridges appear

thicker at the top of the

impression, thus

suggesting heavier

deposition pressure.

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Lateral

Distortion

There is

evidence of

lateralmovement on

the top left and

bottom right ofR1143-1

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Anatomical

Aspects

The oval/pear-

like shape of

this impressionis typically

seen in

thumbs.

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Level 1 Detail

R1143-1 is a

double loop

whorl. Thispattern is

statistically

more prevalenton a thumb.

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R1143-1



R1143 1

Converted to

Black and White

In this image, R1143-

1 was converted to

black and white tomake the viewing of

the ridges easier, as

the ridges in theknown impression are

black.

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D ll MILLARD (A t 2013)



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Dellen MILLARD (August 2013)



Plotted Level 2 Detail in R1143-1a

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R 1143-1 Known (Flat) Right Thumb-Dellen MILLARD

E l ti



Evaluation

The comparison was evaluated to determineif there was agreement, in sequence,

between R1143-1 and the known right

thumb print that had been taken from DellenMILLARD on August 1, 2013 for the present

charges before the court.

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E l ti



Evaluation

As a result of this evaluation, I concluded

that the scene print R1143-1, located on the

rear view mirror inside Tim BOSMA’S truck,was deposited by Dellen MILLARD’S right

thumb.

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V ifi ti



Verification

At the conclusion of the ACE (Analysis,

Compare, Evaluate) stage, the impression

was submitted to Det. BANKS forverification.

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Bosma expert witness