DNA

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DNA
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INTRODUCTION

• WHAT IS DNA?
• deoxyribonucleic acid
• no 2 people can have the same DNA, except
  identical twins.
• the chance of this kind of evidence being wrong
  is 1 in 10 million.

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How is DNA obtained from a crime scene?

• blood
• Hair
• Semen
• Saliva
• bone (marrow)
• Flesh
• Urine
• teeth (pulp)

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DNA AND THE LAW

• Issue can the law keep up with technology?
• Can suspects be compelled to provide samples, and
  how those samples will be taken?
• Do you need a warrant?
• 4th amendment unreasonable search seizure
  (history today) 
• Reasonable suspicion
• What crimes are considered under such a warrant?

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Non-forensic applications

• recently used in Ottawa to identify 2 identical
  twins who had been adopted and accidentally
  separated at birth.
• Paternity cases
• Most powerful uses are in the CJ system

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DNA in law enforcement

• In violent crimes, hair, blood and semen samples
  are more common than fingerprint evidence.
• true for sexual assault cases.
• investigations go much quicker.
• help implicate the guilty, would eliminate the
  innocent
• data base which could include all DNA of
  convicted sex/violent offenders

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DNA in homicide cases

• could be used to help identify a murder weapon.
• For example, a knife with blood stains.
• used to distinguish "copy cat" crimes from serial
  crimes.
• connect crimes committed by the same offender,
  i.e. serial murders.
• determine if more than one offender was involved
• identify deceased/missing persons.

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THE LEGAL QUESTIONS OF DNA EVIDENCE

• The legal question of taking a blood sample from
  an accused person who does not consent is a
  critical issue.
• Is it a form of self-incrimination, or does it
  constitute an unreasonable search?
• Consider a similar case When people are pulled
  over on suspicion of impaired driving, they are
  required to give a sample of their breath.
• If the suspect refuses to give a sample, he/she
  can be charged.

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Differences between drunk driving homicide

• the more serious a crime is, the heavier the
  sentence and the greater the stigma.
• Therefore, the courtsmay be more stringent on
  the issues of constitutional rights.

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Standard of proof

• Another issue in DNA search warrants is the
  determination of a standard or threshold of proof
  to justify the taking of a sample from an
  accused.
• The standard is usually reasonable and probable
  grounds.
• For example, an officer may see some erratic
  driving, smell alcohol on the suspect's breath,
  etc.
• But, DNA testing is more complicated, and may
  warrant a higher standard.

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DNA vs. fingerprinting

• When people are arrested, they are required to
  undergo fingerprinting.
• is not an unwarranted invasion of privacy.
  SOME CANADIAN CASES
• R. v. Alderton
• R. v. Legere  

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Getting the DNA sample

• the police have had to resort to some pretty
  imaginative means to try to get DNA samples
  fromsuspects
• obtaining a tissue that an individual has used to
  blow his nose and thrown away
• Retrieving shed hair
• Ryan Love case

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INTERNATIONAL EXPERIENCE WITH DNA EVIDENCE

• ENGLAND In 1983
• 15 year old girl was raped and murdered.
• In July, 1986, second murder
• Richard Buckland confessed.
• DNA tests showed that the same man killed both
  girls, but Buckland was not that man
• The police asked the 5500 men in the area to give
  DNA sample.
• All gave samples except for a man named Colin
  Pitchfork

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Florida V. Andrew

• The first case in the United States to use DNA
• the accused was convicted ofover 20 cases of
  sexual assault or attempted sexual assault.
• There have even been cases where the accused
  requested a DNA test only tohave it reveal his
  guilt.

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POSSIBLE PROBLEMS WITH DNA EVIDENCE

• Critics of DNA worry that the police may over
  rely on DNA evidence.
• The following problems can arise with DNA
  evidence.
• Contamination problems Heat, humidity, moisture,
  decomposition of a body, time since death,
  temperature where body was stored
• Sexual assault cases the absence of semen does
  not mean that there was no sexual assault.
• great cost and time consumption.

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DATABANKS

• The DNA of convicted sex offenders and other
  violent offenders could be stored into computers
  which would then beaccessible to police forces
• could provide the ability to do split second
  searches andcomparisons.
• would be similar in theory to the Automated
  Fingerprint I.D. System

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Databanks will assist the police in 3 areas

• 1. open cases
• 2. missing persons/unidentified deceased victims
• 3. convicted offenders

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BUT.Civil liberty issues?

•  what information will be stored?
• which offences require an offender to be in the
  computer?
• who will have access tothe information, and for
  what purpose. ?

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Need for DNA standards

• People v. Castro.
• The accused had murdered his neighbor and her 2
  year old daughter.
• State of Minnesota v. Schwartz
• The accused was charged with the first degree
  murder of a stabbing victim.