THE USE OF DNA THE USE OF DNA TECHNOLOGY IN TECHNOLOGY IN

CRIMINAL INVESTIGATION CRIMINAL INVESTIGATION IN TANZANIA.IN TANZANIA.

BY G. MACHUVEBY G. MACHUVE

FORENSIC DNA UNITFORENSIC DNA UNIT

GCLA GCLA

Applications of DNA Applications of DNA technologytechnology

In criminal investigations scientists utilize In criminal investigations scientists utilize DNA profile of a charged person and DNA profile of a charged person and compare it against DNA (human biological compare it against DNA (human biological samples) from the crime scene.samples) from the crime scene.

For instance;For instance; Murder case Murder case Rape casesRape cases Paternity cases Paternity cases Mass disaster – plane crash, fire accidents, Mass disaster – plane crash, fire accidents,

massacre, massacre,

TYPES OF SAMPLES TYPES OF SAMPLES RECEIVEDRECEIVED

Biological samples such as blood, Biological samples such as blood, buccal swab, semen, sweat in buccal swab, semen, sweat in clothes, hair and saliva are usually clothes, hair and saliva are usually received and used to received and used to extract/obtained sufficient quantities extract/obtained sufficient quantities of DNA.of DNA.

EVIDENCE SAMPLES AT CRIME EVIDENCE SAMPLES AT CRIME SCENE LIKELY TO CONTAIN SCENE LIKELY TO CONTAIN

DNA DNA S/NS/N ExhibitExhibit Place where Place where

DNA can be DNA can be foundfound

Source of DNA Source of DNA

11 Knives, Knives, Handles and Handles and blades of blades of knivesknives

Sweat,blood & Sweat,blood & skinskin

22 A capA cap Inner lining Inner lining Sweat, hair, Sweat, hair, dandruffdandruff

33 Spectacles/Spectacles/glasses glasses

Nose bridge & Nose bridge & earlobe earlobe

Sweat, skinSweat, skin

44 Toothpicks, Toothpicks, toothbrushtoothbrush

Edge of Edge of toothpicks, toothpicks, depris in depris in toothbrushestoothbrushes

Saliva Saliva

Cont..Cont..55 Cigarette, cigar pipesCigarette, cigar pipes Cigarette Cigarette

butts, cigar butts, cigar pipes’ mouth pipes’ mouth piece piece

Saliva Saliva

66 Bottle, glass, cans, Bottle, glass, cans, bowls, cupsbowls, cups

Rims and Rims and edges of edges of bottles, cans, bottles, cans, bowls, cupsbowls, cups

Saliva, sweat Saliva, sweat

77 Stamps, envelopesStamps, envelopes Saliva on Saliva on envelope sealenvelope seal

salivasaliva

88 Guns, Guns, Handles, Handles, trigger and trigger and burrel burrel

Sweat & bloodSweat & blood

99 ClothesClothes underpants, underpants, shirts, shirts, trousers, trousers, dresses, dresses, sheets, socks,sheets, socks,

Blood, semen, Blood, semen, sweat, sweat, dandruff, hair dandruff, hair

Cont…Cont…

1010 Foot wearFoot wear Foot wear, Foot wear, sockssocks

Sweat & bloodSweat & blood

1111 Vehicles Vehicles Car seats, seat Car seats, seat belts, steering belts, steering wheel, tires, wheel, tires, window glass, window glass, door knobs, door knobs, buttons, rear buttons, rear mirrors etc…mirrors etc…

Sweat, blood, Sweat, blood, hair, hair, fingerprints & fingerprints & salivasaliva

1212 Body parts Body parts Kidney, liver, Kidney, liver, intestines, intestines, bonesbones

Blood & tissuesBlood & tissues

1313 Toilets Toilets Toilet bowls, Toilet bowls, seats and floorseats and floor

Feaces, urineFeaces, urine

Responsibility of crime Responsibility of crime investigators handling DNA investigators handling DNA

samples;samples;

The investigative officer must accept the The investigative officer must accept the responsibility for seeing that the right types responsibility for seeing that the right types of samples are received to the DNA of samples are received to the DNA laboratorylaboratory

The point is that the evidence samples The point is that the evidence samples should not be exposed to any possibility of should not be exposed to any possibility of destruction, mishandling, contamination, and destruction, mishandling, contamination, and any other conceivable catastrophe that can any other conceivable catastrophe that can be brought on by human or natural error.be brought on by human or natural error.

Responsibility of crime Responsibility of crime investigators handling DNA investigators handling DNA

samples …..samples ….. The point is that the evidence The point is that the evidence

samples should not be exposed samples should not be exposed to any possibility of destruction, to any possibility of destruction, mishandling, contamination, and mishandling, contamination, and any other conceivable any other conceivable catastrophe that can be brought catastrophe that can be brought on by human or natural error.on by human or natural error.

Responsibility of crime Responsibility of crime investigators handling DNA investigators handling DNA

samples …..samples ….. The DNA Scientist has to work with The DNA Scientist has to work with

what has been submitted to the what has been submitted to the Laboratory ad the results will depend Laboratory ad the results will depend on the quality of the on the quality of the sample/evidence submitted.sample/evidence submitted.

The investigating officer at the crime The investigating officer at the crime scene should observe the following scene should observe the following guidelines:guidelines:

GUIDELINES FOR GUIDELINES FOR INVESTIGATING INVESTIGATING

OFFICERSOFFICERS Careful observation of the crime scene Careful observation of the crime scene

prior to handling any evidence prior to handling any evidence samples must be followedsamples must be followed

Store crime scene memory in the form Store crime scene memory in the form of photographs or drawings of photographs or drawings

GUIDELINES FOR GUIDELINES FOR INVESTIGATING OFFICERSINVESTIGATING OFFICERS

Isolate/seal the crime scene using Isolate/seal the crime scene using police warning tapes until forensic police warning tapes until forensic experts arrive experts arrive

Collecting of evidence samples Collecting of evidence samples should be performed by either should be performed by either qualified personnel (crime scene qualified personnel (crime scene examiner) or Government Chemist examiner) or Government Chemist laboratory experts laboratory experts

GUIDELINES FOR GUIDELINES FOR INVESTIGATING OFFICERSINVESTIGATING OFFICERS

Collect all possible evidence Collect all possible evidence (materials) that may link a suspect to (materials) that may link a suspect to a crime scene.a crime scene.

Store gathered information in writing Store gathered information in writing (e.g. note books etc).(e.g. note books etc).

Use appropriate sampling kits in Use appropriate sampling kits in collecting DNA evidence samples.collecting DNA evidence samples.

GUIDELINES Cont…GUIDELINES Cont…

Appropriate sampling kits should be Appropriate sampling kits should be utilized in collecting evidence samplesutilized in collecting evidence samples

Safety and occupational health Safety and occupational health guidelines such as the wearing of gloves, guidelines such as the wearing of gloves, shoes and masks should be observed shoes and masks should be observed

Collect all the possible evidence Collect all the possible evidence (materials) that may link a suspect to a (materials) that may link a suspect to a crime scenecrime scene

GUIDELINES Cont…GUIDELINES Cont…

Store the gathered information either Store the gathered information either in writing or computer etc…in writing or computer etc…

Usually blood or buccal swab Usually blood or buccal swab samples are taken from the samples are taken from the suspected perpetrators so as to suspected perpetrators so as to perform DNA analysis test for profile perform DNA analysis test for profile matching to crime scene samples matching to crime scene samples

Storage and securing of Storage and securing of evidence samples;evidence samples;

Evidence samples should be stored Evidence samples should be stored according to the case fileaccording to the case file

Evidence samples should be stored Evidence samples should be stored separately and appropriately labeled separately and appropriately labeled to avoid contamination of samplesto avoid contamination of samples

Evidence samples should then be Evidence samples should then be locked away in a secured roomlocked away in a secured room

Storage and securing of Storage and securing of evidence samples cont…..evidence samples cont…..

Buccal swab evidence samples Buccal swab evidence samples should be dried out and stored at should be dried out and stored at room temperature whilst raw blood room temperature whilst raw blood evidence samples should be evidence samples should be refrigerated. This is crucial as DNA refrigerated. This is crucial as DNA samples last for an indefinite period samples last for an indefinite period of time when preserved properly.of time when preserved properly.

Handling of Raw blood Handling of Raw blood (5-10mls);(5-10mls);

A white sterile cotton cloth should be A white sterile cotton cloth should be used to soak-up the splattered blood used to soak-up the splattered blood at the crime scene. This cloth should at the crime scene. This cloth should then be air dried and placed in a clean then be air dried and placed in a clean paper envelope. paper envelope.

Blood samples should be packaged in Blood samples should be packaged in a sterile dry glass bottle mixed with a sterile dry glass bottle mixed with anticoagulant such as sodium fluoride. anticoagulant such as sodium fluoride.

Handling of Dried Blood;Handling of Dried Blood;

Scrap off the dried out blood using a Scrap off the dried out blood using a clean scalpel and transfer it to a clean clean scalpel and transfer it to a clean paper envelope. paper envelope.

Alternatively, a white sterile cloth Alternatively, a white sterile cloth moistened with distilled water can be moistened with distilled water can be used to wipe off the dried blood and used to wipe off the dried blood and then air dried and stored in a clean then air dried and stored in a clean paper envelope.paper envelope.

Packaging and labeling Packaging and labeling of evidence samples;of evidence samples;

Evidence samples must be out of Evidence samples must be out of harm's wayharm's way

The type of evidence samples must be The type of evidence samples must be indicatedindicated

There should not be more than one There should not be more than one label label

Permanent (water insoluble) marker Permanent (water insoluble) marker pens should be used in labeling samples pens should be used in labeling samples

Transportation of DNA evidence Transportation of DNA evidence samples to DNA profiling samples to DNA profiling

laboratories;laboratories;

DNA evidence samples have to be DNA evidence samples have to be properly sealed/ packaged and properly sealed/ packaged and labeled so as to prevent them from labeled so as to prevent them from being tempered with.being tempered with.

The DNA samples must be The DNA samples must be accompanied with appropriate accompanied with appropriate authoritative forms (e.g., PF 180) authoritative forms (e.g., PF 180)

Information which should Information which should accompany the samplesaccompany the samples

The type and amount of evidence The type and amount of evidence samplessamples

The origin of the sample The origin of the sample The type of crime committed The type of crime committed The type of testing requestedThe type of testing requested The name and signature of the head The name and signature of the head

of investigationof investigation

Information which should Information which should accompany the samples accompany the samples

cont…cont… The name of the deliverer of the The name of the deliverer of the

samplessamples

DNA samples for parentage DNA samples for parentage identification must have referrals identification must have referrals from court orders, registered from court orders, registered advocates or Social welfare. advocates or Social welfare.

Conditions under which evidence Conditions under which evidence samples are rejected by DNA samples are rejected by DNA

laboratories includelaboratories include;; Missing labels on evidence samplesMissing labels on evidence samples Absence of authoritative forms, PF180, Absence of authoritative forms, PF180,

permitting the legal handling of evidence permitting the legal handling of evidence samplessamples

Unlabelled or destroyed labels on evidence Unlabelled or destroyed labels on evidence samples samples

Evidence samples not listed in the. PF. Evidence samples not listed in the. PF. 180. 180.

Plastic packaging of evidence samples is Plastic packaging of evidence samples is not allowed as this may cause degradation not allowed as this may cause degradation of the biological material of interestof the biological material of interest

Conditions under which evidence Conditions under which evidence samples are rejected by DNA samples are rejected by DNA

laboratories includelaboratories include;;

Dirty packaging of evidence samplesDirty packaging of evidence samples Unpreserved evidence samplesUnpreserved evidence samples More than one label (single labeling More than one label (single labeling

scheme) on evidence samplesscheme) on evidence samples

DNA Analysis Reports DNA Analysis Reports releasedreleased

2005/20062005/2006 Types of Types of casescases

No. of No. of samples samples analyzedanalyzed

Inclusive Inclusive (%)(%)

Exclusive Exclusive (%)(%)

Paternity Paternity 250250 4040 6060

Murder Murder 159159 7373 2727

Rape Rape 5959 -- --

DNA Analysis Reports DNA Analysis Reports releasedreleased

2005/20062005/2006 cont…cont…

No. of No. of samples samples analyzedanalyzed

MaleMale Female Female

Sex Sex identificatioidentification n

33 22 11

FACTORS WHICH MAY FACTORS WHICH MAY AFFECT DNA EVIDENCEAFFECT DNA EVIDENCE

There are several environmental There are several environmental factors that can affect DNA’s integrity factors that can affect DNA’s integrity Heat, sunlight, moisture, bacteria Heat, sunlight, moisture, bacteria

and mold. and mold. Therefore, not all DNA evidence Therefore, not all DNA evidence

samples can be useful for DNA tests samples can be useful for DNA tests

FACTORS WHICH MAY FACTORS WHICH MAY AFFECT DNA EVIDENCEAFFECT DNA EVIDENCE

cont…cont… cross contamination while handling cross contamination while handling

evidence samples; evidence samples; Not wearing appropriate attires – e.g., Not wearing appropriate attires – e.g.,

gloves gloves Stepping on blood at the crime sceneStepping on blood at the crime scene Washing down of evidence located on Washing down of evidence located on

toilets or hand wash basins – rape toilets or hand wash basins – rape casescases

CONCLUDING REMARKSCONCLUDING REMARKS

Crime scene investigators should Crime scene investigators should possess the necessary knowledge on possess the necessary knowledge on collection, packaging and collection, packaging and transportation of DNA evidence transportation of DNA evidence samples.samples.

Confidentiality of DNA evidence Confidentiality of DNA evidence samples should be adhered.samples should be adhered.

THANK YOU FOR YOUR TIME THANK YOU FOR YOUR TIME