Investigative Genealogy Flashcards
1
Q
- The statistics associated with full 17 loci matches will be reduced in cases where we encounter incomplete profiles, relatives and what else?
- What is missing from this sentence? What is the chance that a ———— ———- unrelated person would have the same DNA profile that we are seeing in the evidence sample?
- In contrast to the reference sample, we might expect to see a mixture in the ——— sample
- The allele count at a particular locus represents the number of repeating?
- Where only one peak is seen on the EPG, this is said to be?
- During the Pitchfork case, Jeffreys used a type of repeating (DNA) sequences, different to the ones used today. The repeated segments, in this case dozens or even 100 bases long can be observed. These are referred to as?
A
- The statistics associated with full 17 loci matches will be reduced in cases where we encounter incomplete profiles, relatives and mixtures?
2.What is the chance that a randomly chosn unrelated person would have the same DNA profile that we are seeing in the evidence sample? - In contrast to the reference sample, we might expect to see a mixture in the evidence sample
- The allele count at a particular locus represents the number of repeating base pairs.
- Where only one peak is seen on the EPG, this is said to be homozygous.
- During the Pitchfork case, Jeffreys used a type of repeating (DNA) sequences, different to the ones used today. The repeated segments, in this case dozens or even 100 bases long can be observed. These are referred to as minisatellites.
2
Q
Mini satellites
A
- Highly variable sequences
- Not contributing to the function of genes (non-coding)
- Repeated within the gene
- Sometimes referred to as a variable number tandem repeats (VNTR)
- Range between 9 and 80 base pairs
- Approximately 60% of non-coding DNA consists of short sequences that are repeated over and over.
3
Q
Familial searching
A
- Uses the NDNAD to provide valuable DNA intelligence to further the investigation of undetected serious crime cases, for which a DNA profile has been obtained but for which no match has been reported to date.
- Using the profile data held on the NDNAD the process attempts to identify individuals who have the genetic potential to be related to the individual who left the crime scene profile
- Thus, identifying potential suspects who are not actually represented on the database.
4
Q
Family dispersion is correlated with:
A
Family dispersion is correlated with:
* Higher income
* Higher education
* Criminality runs in families
* Offenders operate close to where they live or in an area with which they are familiar
5
Q
Joseph Kappen
A
- First case worldwide
- Murders of three teenage girls in South Wales circa 1973.
- National DNA Database searched for profiles of possible relatives to murderer < 100 names.
- DNA samples volunteered from relatives.
- Kappen exhumed in 2002 almost 30 years after offence.
- Match & case closed
6
Q
Operation Magnum
Facts
A
- Sandra Newton (aged 16)
body found in 1973. - Struck in face
- Raped and sexually assaulted
- Clothing used as ligature
7
Q
Operation Magnum
Facts 2
A
- The murders remained unsolved for 29 years
- Girls’ underwear stored in FSS laboratory
- In 1998 matching male DNA profiles
- No hits on NDNAD
- In 2000 - Operation Magnum
- Budget: 500 swabs as against 35,000 names.
- Short list of 500 - 353 swabbed; none matched.
8
Q
Operation Magnum
Car thief
A
- In 2000 Familial search
- 22,000 potential hits
- South Wales names checked
- Reduced to 100 possibles
- A local car thief named Kappen appeared which had also appeared in the original enquiry.
9
Q
Operation Magnum
A
- They exhumated Kappen in may 2002 for direct comparison with the crime stain from the original cases.
- They sampled the tooth and femur
- A DNA match was obtained
10
Q
Searching for family members
A
We look for 2 types of relative using 2 different computer programmes:
Parents or Children of the offender
* Siblings (brothers and sisters) of the offender
11
Q
The sibling relationship
A
- Brothers and sisters have the same parents
- They inherit their DNA from these parents
- Logically, they are likely to share more DNA with each other than with unrelated individuals, who have inherited their DNA from a different set of parents.
12
Q
Y STRs
Familiar and screening
A
- If a male appears on the familial lists as a possible parent, child or sibling of the offender, in order for that to be true, his Y-STR must match that of the crime scene stain.
- If it does not, all his male siblings, together with his biological father and all his sons are eliminated as possible offenders.
13
Q
Mitchondrial DNA
Familiar searching
A
- If a female appears on the familial search results lists as a possible parent or sibling of the offender, in order for that to be true, her Mitochondrial DNA profile must match that of the crime scene stain.
- If it is does not match, all her siblings and her children are eliminated as possible offenders. Her father is NOT eliminated in this situation.
14
Q
Familiar searching results
Likelihood ratio
A
- Introduced in January 2008 as a pilot forming part of a validation exercise of new technology.
- A likelihood ratio is a number that represents how likely an individual is to be related to your offender.
- It is calculated based on which alleles (as well as how many) the individual shares with the offender and how rare these are in the general population.
- The higher the number, the more likely that person is to be related.
- A Likelihood ratio allows ranking of both Parent Child and Sibling results.
15
Q
Collecting samples
Perpetrator
A
- First of all, crime scene investigators collect biological materials such as blood, semen, hair or other cellular material.
- Although the DNA molecule will decay over time it has a 521-year half-life (t½) under ideal conditions (-5°C) but degrades quickly when exposed to heat, light, water and air.
- Whether DNA stays viable also depends on how well it’s stored. For example, the oldest DNA recorded was found in Greenland ice and was estimated to be between 450,000 and 800,000 years old.
