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FSC360 > Evolution of DNA Analysis > Flashcards

Evolution of DNA Analysis Flashcards

1
Q

What question does DNA analysis address?

A

Can the DNA-containing body tissue cells be excluded as originating from the same source>

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2
Q

What are good sources of DNA?

A

Blood, semen, saliva, nasal secretions, tooth and bone marrow, vaginal cells, skin cells, roots of hair

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3
Q

What are poor sources of DNA?

A

Urine and feces

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4
Q

What statistics does single source DNA analysis rely upon?

A

Random match probability (RMP)

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5
Q

What is the basic question that RMP boils down to?

A

What is the probability of going into the population at large, picking one person at random and that person having the target DNA profile?

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6
Q

What are the two possible explanations for a DNA profile not being excluded as the source of the target DNA?

A
  1. The reference sample donor is the source of the evidence sample
  2. The reference sample donor cannot be excluded due to coincidence
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7
Q

What is Y-STR analysis?

A

Used to target and analyze DNA variations unique to males.

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8
Q

What special circumstances is Y-STR analysis best suited for?

A

Biological sample contains only a few male cells in a large quantity of female cells
Sexual assault involving multiple male suspects –> assists in determination of the number of assailants
When a reference from a male is not available, but a sample pattern from a paternal male relative is

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9
Q

What is mtDNA analysis?

A

Used to target and analyze DNA variations specific to matrilineal lines.

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10
Q

When is mtDNA used?

A

When hair samples do not contain enough nuclear DNA in their roots
Bone and other samples are heavily degraded.

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11
Q

What are the five main roles of the forensic biologist in criminal cases?

A
  1. Disclose, upon request, relevant case file documentation
  2. Provide clarity to the meaning of the RMP estimate and/or likelihood ratio
  3. Clearly communicate details and relevance of the quality assurance system
  4. Clearly communicate all assumptions made in the DNA profile interpretation process
  5. Use a scientific approach to questions relating to the transfer and persistence of DNA
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12
Q

What was determined about DNA in R. v. Rodgers?

A

DNA has revolutionized the way many crimes are investigated.

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13
Q

When did Canadian investigation agencies begin using DNA?

A

1986

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14
Q

According to the National Research Council, what are potential problems that must be considered when using DNA?

A

Contamination
Degradation
Statistical interpretation
Multiple contributors

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15
Q

Who was the geneticist credited with applying DNA science to forensics?

A

Sir Alec Jeffreys

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16
Q

What challenges were seen to DNA in the early to mid 90s in criminal courts?

A

Scientific validity of “matches” and “non-matches”
Reliability of DNA analysis itself
Reproducibility

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17
Q

What was the first case in Canada in which the court relied on DNA evidence?

A

R. v. Parent

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18
Q

What was the significance of R. v. McNally?

A

First Canadian case in which:
1. DNA evidence was used to implicate and accused, and
2. The admissibility of DNA evidence was challenged.

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19
Q

What was the first DNA case to be considered by the SCC?

A

R. v. Terceira

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20
Q

What was determined in R. v. Terceira about DNA admissibility?

A

The judge merely required to determine a balance of probabilities whether the evidence meets a threshold of reliability.

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21
Q

Which is higher: balance of probabilities standard or standard of proof BARD?

A

BARD

22
Q

What two statutes govern the authorized collection of DNA samples in the forensic context?

A
  1. Criminal Code
  2. DNA Identification Act
23
Q

What does the Criminal Code say about collection of DNA samples in forensic contexts?

A

Permits issuance of DNA warrants for investigative purposes and, after conviction, permit the collection of DNA samples for the National DNA Data Bank (NDDB).

24
Q

What does the DNA Identification Act say about the collection of DNA samples in forensic contexts?

A

Governs NDDB collection orders.

25
Q

What are the two NDDB databases?

A

Convicted offenders index (COI)
Crime scene index (CSI)

26
Q

What is the principle of DNA collection after sentencing?

A

DNA profiles can assist in the early detections, arrest and conviction of offenders.

27
Q

What was found about DNA in R. v. S.A.B.?

A

DNA warrant provisions do not violate s. 8 of the Charter.
Standard of reasonable grounds sufficient for DNA warrants

28
Q

What was established in R. v. Rodgers about DNA?

A

Reasonable to collect DNA samples from designated convicted offenders for the NDDB.
Collection procedures do not violate the offender’s s. 7 and 8 Charter rights.

29
Q

What does a “hit” in the NDDB mean?

A

Provide grounds for police to request a DNA warrant for comparison.

30
Q

Differentiate between DNA requests in primary and secondary designated offences.

A

Primary: Once the prosecutors requests the order, the Court SHALL make the order.
Secondary: Once the prosecutor requests the order, the court MAY make the order.

31
Q

What are the limitations of the DNA identification act?

A

Familial searching is prohibited
NDDB only contains profiles of convicted offenders
DNA Identification Act does not consider DNA profiles outside of the NDDB

32
Q

Describe the case of the Golden State Killer.

A

Estimated to have committed multiple murders, 50 rapes and over 100 burglaries.
Killer’s DNA profile uploaded and family tree constructed leaving Joseph DeAngelo as main suspect.
DeAngelo’s DNA collected from the door handle of car and discarded tissue
Could not be excluded as source of GSK DNA
Entered guilty plea

33
Q

Describe the case of Christine Jessop

A

Guy Paul Morin arrested for the murder.
Found not guilty in first trial, which was appealed by the Crown.
Found guilty of first degree murder in second trial
DNA evidence exonerated Morin
Toronto Police identified an alternative suspect through forensic genetic genealogy.

34
Q

Describe the case of R. v. Stillman.

A

Refused to provide samples.
Hair samples and dental impressions taken forcefully.
DNA also obtained from discarded mucous sample.
Re-arrested months later and more samples taken by force.
Convicted of 1st degree murder, conviction upheld upon appeal.

35
Q

What is the general rule regarding discarded DNA?

A

There is no REP in a person’s garbage. Challenges with respect to s. 8 thus rarely succeed.

36
Q

What did the SCC decide in R. v. Stillman?

A

Charter rights were violated in all collections.
Forceful samples not allowed.
Mucous sample would not bring admin of justice into disrepute, new trial ordered.

37
Q

Describe a case in which DNA evidence was taken without a warrant when the suspect was not in police custody.

A

Chewing gum survey.
Didn’t violate Charter rights as suspect chose to participate and discarded gum in public.

38
Q

Describe a case in which DNA was taken without a warrant when the suspect was not in police custody but was under some degree of police control.

A

R. v. Marini
DNA obtained from cigarette butts discarded by suspect during voluntary police interview.
No Charter violation.
No REP in discarded butts and could have chosen not to smoke or take the butts with him.

39
Q

Describe the case of R. v. Nguyen

A

R. v. Nguyen (p. 422 of readings). Police devised a plan to obtain DNA from the suspect to circumvent his refusal to provide bodily samples. Police offered the suspect a piece of gum during transport to and from the courthouse. Two DNA samples obtained from the discarded chewing gum. ONCA found that s. 8 was breached because, in the circumstances, Nguyen did not relinquish his privacy interest in the gum by discarding it. The evidence was admitted under section 24(2) because the officers were acting in good faith, the evidence was discoverable, the seizure did not interfere with the appellant’s dignity or bodily integrity. Further, considering the seriousness of the offence (first degree murder) and the importance of the DNA evidence, its exclusion would bring the administration of justice into disrepute.

40
Q

What are some potential interpretation problems with DNA?

A

Accidental DNA transfer between one DNA sample and another
Secondary DNA transference between parts of the complainants body

41
Q

What is the issue with accidental DNA transfer?

A

False matches

42
Q

What is the issue with secondary DNA transference?

A

Reliable inferences

43
Q

What is a case example of accidental DNA transfer?

A

Phantom of Heilbronn

44
Q

Describe the case of Lukis Anderson.

A

Wrongly implicated in the robbery and murder of a Silicon Valley millionaire
Arrested after DNA was found under the deceased’s fingernail
Alibi: hospitalized as a result of intoxication on the night of the murder

45
Q

What was the first case in which STRmix was challenged in Canada?

A

R. v. Dean

46
Q

What probability form does STRmix rely on?

A

Likelihood ratios

47
Q

What were the arguments against the qualifications of the forensic biologist in R. v. Dean?

A

No access to and no ability to review the source code in STRmix
Not shown adequate proficiency in relation to a four person mixture
Forensic biologist demonstrated a clear bias in favour of STRmix.

48
Q

What was held in R. v. Dean?

A

STRmix is reliable and source code does not need to be known
Adequate proficiency
Expert understood his duty to the court.

49
Q

WHat are the limits to inferences arising from DNA analysis?

A

Can’t determine when it was deposited
Cannot determine how it was deposited
Might not be possible to determine from what substance it arose
Innocent transfer/indirect transfer is a possibility

50
Q
A

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