lecture 3 bpa lim 2013

8/10/2019 Lecture 3 BPA Lim 2013

1/9

2013/9/6

1

Lecture 2: DNA analysis

Lecture 3: Bloodstain Pattern Analysis

Lecture 4: Fingerprints

Forensic Biology

Dr. B. L. Lim

Associate Professor

School of Biological Sciences

[email protected]

Tel: 22990826

Contents

1. Introduction to bloodstain pattern analysis

2. Discussion on various bloodstain patterns

3. Determination of impact site by stringing method

4. Case sharing and discussion

References

1. Tom Bevel and Ross M. Gardner, Bloodstain patternanalysis with an introduction to crime scene reconstructionCRC Press, 1997.

2. The website of J. Sklemo Forensic Consulting Inc. can beviewed at : http://bloodspatter.com/bloodstain-resources.

3. The website of Hemospat can be viewed at:

http://hemospat.com/index.php. 4. Dr. Henry Cheung, former Government Lab Scientific

Officer.

The book and the two websites are used as references toprepare for this lecture.

What is BPA ()?

Interpretation of patterns, shapes and sizes of

bloodstains in order to reconstruct the event of

incident or crime.

Note: The terminology of the International Association of

bloodstain Pattern Analysis (IABPA) is used.

http://hemospat.com/terminology/index.php

Blood

Blood contains wbc, rbc and platelets

suspended in plasma (55%).

Composed of water (91%), proteins (8%) and

other materials.

An adult has a blood volume of 5 to 6 L.

Presumptive test: KM test

Confirmatory test: a) Takayama crystal testb) ABAcard HemaTrace Kit

Impact on different surfaces

Drip blood

Wooden floorSmoothsurface

Source: J. Slemko Consulting
mailto:[email protected]://bloodspatter.com/bloodstain-resourceshttp://hemospat.com/index.phphttp://hemospat.com/index.phphttp://hemospat.com/index.phphttp://hemospat.com/index.phphttp://hemospat.com/index.phphttp://hemospat.com/index.phphttp://hemospat.com/index.phphttp://hemospat.com/index.phphttp://bloodspatter.com/bloodstain-resourceshttp://bloodspatter.com/bloodstain-resourceshttp://bloodspatter.com/bloodstain-resourceshttp://bloodspatter.com/bloodstain-resourceshttp://bloodspatter.com/bloodstain-resourceshttp://bloodspatter.com/bloodstain-resourceshttp://bloodspatter.com/bloodstain-resourcesmailto:[email protected]


2/9

2013/9/6

2

Source: science.howstuffworks.com

Bloodstain patterns

Contact/transfer bloodstains

Swipe pattern


Drip Pattern Swipe Pattern

Source: hemospat.com

Wipe and Skeletonized Patterns


3/9

2013/9/6

3

Arterial Spurting (or Gushing) Pattern

Arterial Spurting Pattern()


Transfer/Contact Patterns

(Of Fingers)

(Of Screwdriver)

Knife blade

Footwear

Pattern transfer

Cast-off Pattern()

Impact spatters ()

The blood pattern is created when a blood

source receives a blow or force resulting in the

random dispersion of smaller drops of blood.


4/9

2013/9/6

4

Impact spatters ()

1)Low velocity impact spatter (LVIS)( )- size of major stains: >4mm

2)Medium velocity impact spatter (MVIS)(

)

- size of major stains: 1 to 4mm

3)High velocity impact spatter (HVIS)( )

- size of major stains: 1 mm or < 1 mm

Low Velocity Impact (LVIS) Medium Velocity Impact (MVIS)

High Velocity Impact Spatter (HVIS)

100 fps

Low velocity impact spatter

Exampleblood in blood

Wall

Wound


Medium velocity impact spatter

Example:

1. Fisting

2. hit by rod

3. fighting

Source: Henry Cheung

MVIS


High velocity impact spatter

Example

Shooting

Mist like

pattern


5/9

2013/9/6

5

Blood patterns resulted from gun shot

High velocity impact spatter Among fine particles and larger droplets,

aerosol or atomized particles are produced.

These atomized particles or droplets cannot

travel more than 4 ft. in distance

Source: fig. 4.12 of Bloodstain pattern analysis with an introduction to crime scene

reconstruction by Tom Bevel and Ross M. Gardner 1997 CRC Press

Impact spatter

How blood drops travel and strike at target


Source: Henry Cheung

Formation of Secondary stains


6/9

2013/9/6

6

Source: Bloodstain pattern analysis with an introduction to crime scene reconstruction by

Tom Bevel and Ross M. Gardner 1997 CRC PressSource: HemoSpat

Other pattern

Measuring impact site()

Stringing Method

Measuring impact site

Stringing Method

1) Select several representative stains

2) Measure impact angle for each bloodstain

3) Use a string to tracethe path of the blooddroplet traveling from the impact site to the

striking surface

4) All strings should converge (intercept??) at

the impact site

Blood Drops Impact Angles

(Jackson & Jackson)

Measuring impact angle

Sin = width/length

Width

Length

Note: usually smaller than the actual angle

Blood drop travel in this direction
http://hemospat.com/terminology/index.php?cat=misc&sub=fly-spotshttp://hemospat.com/terminology/index.php?cat=misc&sub=fly-spots


7/9

2013/9/6

7

2.3 cm

3.3 cm

1.3 cm

Trace the path of traveling blood

droplet

By placing a line through the long axis of the

selected bloodstain

Direction

of

traveling

Point of Origin

(Jackson & Jachson)

A

C

BImpact site

All strings (brown, red and green) intercept at the impact site

protractor


8/9

2013/9/6

8

Source: hemospat.com

SummaryCase sharing and discussion

Case 1: A silence murder case

Case 2: Searching for missing culprit using

paternity analysis

Case 3: A wounding case in a shopping mall. Case 4: Police killer

Case 1: A silence murder case

Case Scenario

A murder case was solved by latent DNA evidence

and bloodstain pattern analysis. The details are as

follows:

1. A victim was chopped and died at the scene

2. A bloodstained knife was seized by police and

submitted to forensic laboratory

3. Blood on the blade of the knife and latent DNA onthe gauze wrapping the handle were collected and

typed

Case Scenario

4. The results of DNA typing indicated that the blood

could have come from the victim and the latent DNA

came from an unknown male

5. This indicated that the knife was likely to be used to

chop the victim, and an unknown male had touched

the handle of the knife

6. Half year later, there was a fight among a group of

triad member. Blood found at the scene was

submitted to forensic laboratory

7. DNA results indicated that the DNA types of the

blood matched those of the latent DNA on the gauze.
http://hemospat.com/terminology/index.phphttp://hemospat.com/terminology/index.php


9/9

2013/9/6

Case Scenario/Trial

8. The control blood sample was collected from the

wounded person. Results indicated that his DNA types

matched those of the latent DNA on the gauze.

9. During the trial, he claimed that he had been at the

scene but had not participated into the attack. He had

held the knife and blood had splashed on it.

10.However, the opinion drawn from bloodstain pattern

analysisindicated that the knife was likely to be used to

chop someone and this personsDNA matched that on

the blade.

11.He was sentenced to life imprisonment.

Case 2: Searching for missing culprit by

parentage analysis

A bloodstain found at scenebut the control sample from

the suspect was not

available .

Searching for missing

culprit using paternity

analysis () for

crime investigation.

Alleged

mother

Alleged

fatherBlood

Case 3: A wounding case in a shopping

mall

Case Scenario

Three young men attacked another man in a shoppingmall.

They left the scene and took a taxi.

They were arrested by police at a police road block. Bloodstains were found on a T-shirt from one of the

men (The picture refers). The T-shirt was submitted toforensic lab for examination.

Results of DNA test indicated that the blood couldhave come from the victim.

Case Scenario

1. During the trial, the defense lawyer insisted that hisclient had a contact with a wounded person in themall and the blood was then transferred to one ofhis clients clothing. Therefore, his clients did notattack the victim.

2. The court was adjourned. Police asked forensic labto further analyze bloodstain pattern on the exhibit.

.

.

..

Front Back

A wounding case in a shopping mallIdentify serial killer by matching with DNA left at crime scenes

Tsui Po-ko (17 May 1970 17 March 2006) was a police

constable who was implicated in a number of crimes,

including bank robberyand murders. He died when he and

another police constable shot each other in a gun battle in a

Tsim Sha Tsui underpass.

Tsui was found responsible formurderingconstable Leung Shing-yan and

stealing his revolver in March 2001. Answering a noise complaint in Tsuen

Wan, on March 14, 2001, Leung was shot five times at close range. His

revolver, and one extra clip of six bullets were missing. The noise complaint

was apparently bogus, and was made from an untraceable mobile phone.

Some 3,000 people, of which 2,000 police officers, were interviewed by the

police, yet the perpetrator escaped detection. Later, forensic tests (PCR-STR,

Polymerase Chain Reaction-Short Tandem Repeats)found that the DNAon a mask leftat thecrime scenematched Tsui's.

Case 4: Police killer
http://www.worldlingo.com/ma/enwiki/en/Bank_robberyhttp://www.worldlingo.com/ma/enwiki/en/Murderhttp://www.worldlingo.com/ma/enwiki/en/Murderhttp://www.worldlingo.com/ma/enwiki/en/Murderhttp://www.worldlingo.com/ma/enwiki/en/DNAhttp://www.worldlingo.com/ma/enwiki/en/Crime_scenehttp://www.worldlingo.com/ma/enwiki/en/Crime_scenehttp://www.worldlingo.com/ma/enwiki/en/Crime_scenehttp://www.worldlingo.com/ma/enwiki/en/DNAhttp://www.worldlingo.com/ma/enwiki/en/Murderhttp://www.worldlingo.com/ma/enwiki/en/Bank_robbery

lecture 3 bpa lim 2013

Documents