AC 1.2
Forensics and DNA
● DNA stands for Deoxyribonucleic acid, with an individual inheriting half of their DNA
from their father and half from their mother.
○ DNA profiles are derived from samples such as semen, saliva and blood.
■ To help investigate crime police have intelligence databases which
provide information on a certain topic which may be relevant to their
criminal investigation.
● Example:
○ PNC-police national computer
■ contains information on car insurance and motor related information,
as well as the fingerprint database
○ The national DNA database
■ the world's first DNA database created in 1995 for England and Wales.
■ Scotland and Ireland have their own DNA databases and submit
profiles to NDNAD.
● Modern world of dna
○ the police are accompanied by a range of forensic experts to help in
investigations
○ the police discuss actions and usefulness of various forms of evidence
■ There is limited access to the crime scene, and the police recover
evidence scientifically.
○ two types of DNA samples that can be taken from suspects;
■ non-intimate samples
● Non-intimate samples can be taken without a person's consent
and are most commonly mouth swabs.
■ intimate samples
● Intimate samples on the other hand cannot be taken without
the person's consent, and include things such as blood and
semen.
● Samples are often taken from volunteers as well as criminals, suspects and any
evidence present at a crime scene.
○ produces large databases in which many samples can be compared,
increasing the chance of finding an offender.
■ the databases arent inclusive of everyone, and doesnt always comes
up with a result despite days of testing.
● all DNA being kept on database
○ leds to a miscarriage of justice
■ Example: David Butler
● wrongly imprisoned for murder through DNA
○ DNA sample was on record after he willingly gave it as
part of an investigation = burglary at his mothers home
years earlier.
, ● DNA was found to be a partial match of poor quality,but despite
this he was still found guilty
○ Butler had a rare skin condition,
■ leaving flakes of skin wherever he goes;
● he worked as a taxi driver
○ his dna may have been passed on this way to the
victim before the murder
■ no concrete evidence he did commit a crime.
● highlight that findings of trace amounts
of dna can falsely implicate a person
however.
● March 2012
○ the database contained an estimated 5,950,612 individuals
■ DNA has helped in more than 350,000 investigations.
● Weakness :
○ there are still a lot of people who are not in the
database.
○ Not all crimes committed are by people who have
already committed crimes
■ in these cases the database is rendered
● useless it is taken from a crime scene
and stored for later testing
○ many criminals also serving long stretches in prison
■ much of the DNA samples are from people who
are already in prison
● dont have the availability to commit
crime = limiting the usefulness of the
database.
● Strengths:
○ DNA profiles are derived from samples
■ semen, saliva and blood.
● dna profiling examining discrete parts of individuals
● dna varying greatly from one person to another
○ when an exact or very close match is made it suggests
great accuracy.
● Weakness:
○ It doesn't work for identical twins
■ They share 100% of the same dna.
○ It is also not exclusive to all dna types, and collecting certain types of dna is
considered to be a violation of privacy.
● Example : Colin Pitchfork
○ DNA databases failing successfully
■ a murder of a young girl occured in a small neighbourhood
■ the police believed the offender was local
Forensics and DNA
● DNA stands for Deoxyribonucleic acid, with an individual inheriting half of their DNA
from their father and half from their mother.
○ DNA profiles are derived from samples such as semen, saliva and blood.
■ To help investigate crime police have intelligence databases which
provide information on a certain topic which may be relevant to their
criminal investigation.
● Example:
○ PNC-police national computer
■ contains information on car insurance and motor related information,
as well as the fingerprint database
○ The national DNA database
■ the world's first DNA database created in 1995 for England and Wales.
■ Scotland and Ireland have their own DNA databases and submit
profiles to NDNAD.
● Modern world of dna
○ the police are accompanied by a range of forensic experts to help in
investigations
○ the police discuss actions and usefulness of various forms of evidence
■ There is limited access to the crime scene, and the police recover
evidence scientifically.
○ two types of DNA samples that can be taken from suspects;
■ non-intimate samples
● Non-intimate samples can be taken without a person's consent
and are most commonly mouth swabs.
■ intimate samples
● Intimate samples on the other hand cannot be taken without
the person's consent, and include things such as blood and
semen.
● Samples are often taken from volunteers as well as criminals, suspects and any
evidence present at a crime scene.
○ produces large databases in which many samples can be compared,
increasing the chance of finding an offender.
■ the databases arent inclusive of everyone, and doesnt always comes
up with a result despite days of testing.
● all DNA being kept on database
○ leds to a miscarriage of justice
■ Example: David Butler
● wrongly imprisoned for murder through DNA
○ DNA sample was on record after he willingly gave it as
part of an investigation = burglary at his mothers home
years earlier.
, ● DNA was found to be a partial match of poor quality,but despite
this he was still found guilty
○ Butler had a rare skin condition,
■ leaving flakes of skin wherever he goes;
● he worked as a taxi driver
○ his dna may have been passed on this way to the
victim before the murder
■ no concrete evidence he did commit a crime.
● highlight that findings of trace amounts
of dna can falsely implicate a person
however.
● March 2012
○ the database contained an estimated 5,950,612 individuals
■ DNA has helped in more than 350,000 investigations.
● Weakness :
○ there are still a lot of people who are not in the
database.
○ Not all crimes committed are by people who have
already committed crimes
■ in these cases the database is rendered
● useless it is taken from a crime scene
and stored for later testing
○ many criminals also serving long stretches in prison
■ much of the DNA samples are from people who
are already in prison
● dont have the availability to commit
crime = limiting the usefulness of the
database.
● Strengths:
○ DNA profiles are derived from samples
■ semen, saliva and blood.
● dna profiling examining discrete parts of individuals
● dna varying greatly from one person to another
○ when an exact or very close match is made it suggests
great accuracy.
● Weakness:
○ It doesn't work for identical twins
■ They share 100% of the same dna.
○ It is also not exclusive to all dna types, and collecting certain types of dna is
considered to be a violation of privacy.
● Example : Colin Pitchfork
○ DNA databases failing successfully
■ a murder of a young girl occured in a small neighbourhood
■ the police believed the offender was local
