DNA Testing Overview and Applications

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Questions and Answers

What is the first step in collecting wet body fluids on non-porous surfaces?

Apply distilled water to the stain

Use a double-tipped swab to collect the stain

Absorb the stain onto a sterile cotton swab (correct)

Scrape the stain off the surface

What should be done with the swabs after collecting wet body fluids?

Use Q-tips to ensure better absorption

Label the swab box with the location of recovery (correct)

Compress the swabs to extract more fluid

Place swabs in a water solution for preservation

For large porous items with wet body fluids, what is the recommended action?

Cover the item with distilled water

Cut out stained areas or submit the entire item (correct)

Leave the item in its location

Swab the area without any preparation

How should dried body fluid stains be collected from surfaces?

By submitting the item directly to the laboratory Signup and view all the answers

What is a key caution when collecting dried body fluid stains?

Do not scrape any crusts to prevent airborne flakes Signup and view all the answers

What is the maximum number of saturated swabs recommended for submission?

4 Signup and view all the answers

What type of swabs should not be used when collecting body fluids?

Double-tipped swabs and Q-tips Signup and view all the answers

What is one of the main reasons for collecting stains as dry items when possible?

To ensure the evidence is in its most concentrated form Signup and view all the answers

What is the main purpose of mitochondrial DNA testing?

To improve reliability in missing persons cases. Signup and view all the answers

Which type of DNA testing is specifically utilized for paternity or lineage cases?

Y-chromosome DNA testing. Signup and view all the answers

When is the Virginia DNA Data Bank used?

When DNA profiles do not match known samples. Signup and view all the answers

What limitation does Y-chromosome DNA testing have?

It does not provide a DNA profile for female subjects. Signup and view all the answers

What type of samples can be included in a criminal paternity or maternity case analysis?

Blood or buccal samples from the victim, suspect, and child. Signup and view all the answers

What does the term 'mitotype' refer to in mitochondrial DNA testing?

The linear order of DNA building blocks. Signup and view all the answers

Why might some DNA profiles not be suitable for searching against the Virginia DNA Data Bank?

They are mixture profiles containing DNA from multiple people. Signup and view all the answers

Which statement is true regarding the elimination of contributors from DNA evidence?

Statistical calculations are used to provide weight to conclusions. Signup and view all the answers

What identifiable body characteristics can be isolated from fetal tissue that is 10 to 12 weeks old?

Hands and feet. Signup and view all the answers

At what gestational age may identifiable body characteristics be challenging to isolate from the fetus?

Less than 10 weeks old. Signup and view all the answers

What assistance may be required to isolate fetal tissue from maternal tissue?

Assistance from the medical doctor performing the procedure. Signup and view all the answers

What is a limitation for requesting the analysis of trace DNA evidence for lesser felony crimes?

Requests are limited to two samples per case. Signup and view all the answers

What should be done before submitting a large number of items for DNA analysis?

Contact a DNA examiner or supervisor. Signup and view all the answers

What factors determine the determination of probative evidence?

Type of case, evidence collected, and victims and perpetrators involved. Signup and view all the answers

What happens if additional evidence submissions are needed?

Communication occurs between the assigned examiner and the investigator. Signup and view all the answers

What type of evidence can still be collected from washed clothing and bedding?

Trace evidence and biological substances Signup and view all the answers

What should be done if a Physical Evidence Recovery Kit (PERK) has been collected?

Do not submit the bedding until the PERK is evaluated Signup and view all the answers

What must be collected from the suspect's body in a digital penetration case?

Swabs from each hand combined into a single swab box Signup and view all the answers

Which item is used to collect known samples for elimination purposes?

Buccal Swabs Kit Signup and view all the answers

What should be avoided when collecting swabs from the suspect's fingers?

Collecting a separate swabbing from each finger Signup and view all the answers

During the collection of the suspect's clothing, what is recommended?

To have the suspect stand on a clean sheet of paper Signup and view all the answers

What types of materials may be found on the suspect’s clothing during collection?

Vaginal fluid and saliva Signup and view all the answers

What is the main purpose of the Suspect Physical Evidence Recovery Kit (SPERK)?

To recover physical evidence from the body of a sexual assault suspect Signup and view all the answers

What is required for DNA analysis of misdemeanor offenses that are not sex-related?

A written request from the Commonwealth’s Attorney Signup and view all the answers

What must be submitted to the laboratory before conducting a DNA analysis?

Known samples and the most probative item(s) Signup and view all the answers

If an item of evidence is wet, what should be noted before submission?

It must be indicated on the RFLE form Signup and view all the answers

What is the current policy regarding control swabs?

They no longer need to be collected Signup and view all the answers

In a sexual assault case, which item should be included in the first submission of evidence?

Victim Physical Evidence Recovery Kit (VPERK) Signup and view all the answers

What is recommended before submitting evidence from a 'cold case'?

Consult with a Forensic Biology Section examiner Signup and view all the answers

What should the investigator do if additional evidence is needed after the initial submission?

Submit additional items at a later date Signup and view all the answers

Which type of evidence is specifically mentioned as not requiring analysis?

Sex-related misdemeanor offenses Signup and view all the answers

Study Notes

DNA Testing

Examiners use statistical calculations to determine if a DNA profile from evidence matches a known sample.
Mitochondrial DNA testing improves the reliability of identification.
Mitochondrial DNA testing is used in missing persons and body identification cases.
Mitochondrial DNA testing is also used in serious felony investigations when other methods yielded limited results.
Y-chromosome DNA testing is used in cases with high ratios of female DNA to male DNA.
Y-chromosome DNA testing is used to determine lineage such as paternity or missing persons cases.
Y-chromosome DNA testing does not yield searchable profiles and is not useful without known reference samples.

Virginia DNA Data Bank

Evidence profiles that do not match known samples will be searched against the Virginia DNA Data Bank and nationally.
DNA profiles from mixtures (more than one person) and partial profiles are not suitable for the Virginia DNA Data Bank.

Criminal Paternity/Maternity

Forensic Biology performs DNA analysis in incest or rape cases that resulted in a child.
Blood or buccal (cheek) samples from the victim, suspect, and child are sent for comparison.

Wet Body Fluids on Non-Porous Surfaces

Wet stains should be collected with sterile cotton swabs until saturated.
Do not use double-tipped swabs or Q-tips.
Place saturated swabs in a swab box labeled with the location of collection.

Wet Body Fluids on Porous Surfaces

Submit the air-dried item of evidence if possible.
Cut out stained areas for large items.
Swab the stained area with sterile swabs, concentrating the stain as much as possible.

Dried Body Fluids Stains

Submit the item of evidence whenever possible.
Swab stains and submit the swabs to the laboratory.
For large items, cut out stained areas or recover stains with moistened sterile swabs.

Clothing and Bedding

Submit even washed clothing and bedding if other evidence does not yield probative information.
Consult with the lab prior to submitting bedding or similar items.

Suspect Physical Evidence Recovery Kit (SPERK)

SPERK is used within 24 hours of a sexual assault.
Collect a buccal sample from the suspect for comparison with foreign secretions and hairs from the victim.
Collect foreign secretions and trace evidence from the suspect's body and underpants.

Sexual Assault Suspect’s Clothing

Collect the suspect’s clothing worn during the assault.
Have the suspect stand on a clean sheet of paper while disrobing to collect trace evidence.

Buccal Swabs Kit

Used to collect known samples from a victim, suspect, or third party for elimination purposes.

Fetal Tissue

Submit tissue collected from an aborted fetus.
Tissue from an aborted fetus may be 10 to 12 weeks old and contain identifiable body characteristics.
Assistance from a medical professional may be required to isolate fetal tissue from maternal tissue.
Refrigerated tissue should be submitted quickly.

General Reminders

Requests for analysis of potential “trace” DNA evidence are limited to two samples per case for lesser felony crimes.
Prior to submitting a large amount of evidence, contact a DNA examiner/supervisor to identify the items most relevant to the case.
Submit only the most probative items.
Consult with a Forensic Biology Section examiner or supervisor when submitting evidence from a cold case.
If evidence cannot be dried before submission, indicate on the RFLE form that the item is wet.
Do not submit control swabs.
DNA analysis of evidence associated with misdemeanor offenses will only be analyzed based on a written request from the Commonwealth’s Attorney.
Submit all appropriate known samples before the DNA analysis of evidence.

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Description

This quiz explores the critical aspects of DNA testing, focusing on methodologies such as mitochondrial and Y-chromosome testing. Learn how these techniques are applied in criminal investigations, missing persons cases, and paternity testing. Additionally, it discusses the role of the Virginia DNA Data Bank in evidence matching and profile searching.