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Analyst Training > Contamination, Screening, Lab Technique > Flashcards

Contamination, Screening, Lab Technique Flashcards

1
Q

what is the amended report (AR) 3125

A

subsection of ISO 17025 that applies directly to forensic testing laboratories

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2
Q

what does ANAB stand for and what does it do

A
  • ANAB = ANSI (American National Science Institute) National Accreditation Board
  • accredits the LSPCL every four years
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3
Q

define analytical control

A

a sample used to demonstrate that a method works correctly and then ensures the data is valid

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4
Q

explain the combined DNA index system (CODIS)

A
  • US national DNA database that is maintained by the Federal Bureau of Investigation (FBI)
  • there are twenty CODIS core STR loci required for upload of DNA profiles into the national DNA database
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5
Q

what is direct contamination

A

transfer of DNA from source of contamination to evidentiary item or sample

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6
Q
A
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7
Q

what is indirect contamination

A

transfer of DNA from the source of contamination to the evidentiary item or sample through an intermediary

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8
Q

what is an internal audit, how often are they performed, and who performs them

A
  • performed by LSPCL employees who are qualified auditors
  • ISO/AR internal audit: every year; LSPCL audits only follow these standards
  • - auditors must pass a course and competency test
  • FBI QAS internal audit: auditors must be a qualified DNA analyst and pass the FBI auditor course
  • - must meet requirements of QAS appendix C
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9
Q

what is an internal validation

A

the accumulation of test data within the laboratory to demonstrate that established methods and procedures perform as expected

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10
Q

what does ISO/IEC stand for and what does it do

A
  • the acronym for the joint technical committee of the Internal Organization for Standardization and the Internal Electrotechnical Commission
  • ISO/IEC develops, maintains, and promotes standards covering multiple industries
  • ISO 17025: standards for testing laboratories
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11
Q

what is a performance check

A

a quality assurance measure to assess the functionality of laboratory critical equipment and instruments

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12
Q

examples of personal protective equipment (PPE)

A

lab coat, mask, gloves, etc.

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13
Q

what are quality assurance standards (QAS)

A

standards set by the FBI that are specific to DNA testing laboratories

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14
Q

what does SWGDAM stand for and what does it do

A
  • the acronym for the Scientific Working Group on DNA Analysis Methods
  • SWGDAM provides recommendations to the FBI and the United States forensic DNA community on quality assurance standards, research, protocols, and methodologies
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15
Q

what is the abacard hematrace test

A
  • presumptive test for blood
  • indicates human/non-human source for blood
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16
Q

what is acid phosphatase and what is it used for

A
  • presumptive test for seminal fluid
  • AP is an enzyme secreted in higher amounts by the prostate gland than anywhere else
17
Q

what does azoospermic mean

A
  • absence of sperm in ejaculate
  • result of vasectomy
18
Q

what is bulk evidence

A

any physical items collected at the crime scene

19
Q

what are consumed items

A

when the entirety of the original evidence is used for testing; there is no excess to retain or re-test

20
Q

what is contamination

A

the unintentional introduction of exogenous DNA into a sample or control during DNA testing

21
Q

what are cuttings

A
  • taken when the evidence examined is porous and there is an expectation that the biological material intended for analysis can penetrate past the surface
  • for evidence, 1cm^2 - 1.5cm^2 is removed
  • for references, 0.5cm ^2 - 1cm^2 is removed
  • prepped for extraction in flip-cap 1.5mL conical tubes
22
Q

what is documentation

A
  • notes of the examination contemporaneous
  • includes submission numbers, exhibit numbers, item descriptions, observations, photographs, SP#s, reagent lot numbers, individuals involved, and chain of custody
23
Q

what is evidence

A
  • anything that is collected from the crime scene
  • swabs, bulk (weapons, clothing, tools, consumables), sexual assault kits (clothing, bedding, towels, condoms, devices), miscellaneous (vehicles, bones, hairs)
24
Q

what are extraction sample types

A
  • sexual assault kit samples: intimate and trace samples are processed differently
  • blood: lots of DNA
  • trace/contact: skin cells
  • hair: root only
    * hair shaft required for mitochondrial DNA testing
25
Q

what is the “forensic question”

A
  • the probative nature of the evidence
  • WHO is on the evidence
  • HOW do we get to the WHO on the evidence
  • WHAT does getting the WHO on the evidence mean
26
Q

what is the high dose hook effect

A
  • occurs with excess antigen which binds to the stationary antihuman antibody in the “T” area
  • prevents the mobile antibody-antigen complex from binding
27
Q

what is microscopy for spermatozoa

A
  • confirmatory test for spermatozoa (no longer performed at LSPCL)
  • the presence of semen in questioned specimens can be confirmed by the observation of spermatozoa
  • utilizes christmas tree stain
28
Q

what does oligospermic mean

A
  • lower than normal sperm count
  • > 15 million sperm per 1 mL semen
29
Q

what is the phenolphthalein test

A
  • presumptive test for blood
  • tests presence of hemoglobin
30
Q

what is the prostate specific antigen test (PSA)

A
  • presumptive test for seminal fluid
  • tests for P30; only found in semen
31
Q

what is screening

A

the examination and sampling of evidence for DNA analysis or preservation

32
Q

what is serology

A

the testing and identification of bodily fluids

33
Q

what are sexual assault kits (SAK)

A
  • swabs, trace evidence (suspect hairs, debris), and clothing collected by trained medical professionals (SANE nurses)
  • intimate swabs are forwarded to differential extraction
  • non-intimate swabs are presumptively tested (AP test)
34
Q

what is a state police number (SP#)

A
  • unique to every case processed at LSPCL
  • ex: #####-24
35
Q

what are swabs

A
  • a stick or rod with a fiber or foam-like material end used to collect biological substances
  • for evidence, 1/2 - 2 swabs are taken
  • for references, 1/2 - 1 oral reference swab is taken
  • prepped for extraction in flip-cap 1.5mL conical tubes
36
Q

tips for large volume pipetting

A
  • insert pipette at an angle into the tube for ejecting/inserting liquid
  • insert pipette tip into existing liquid
37
Q

example pipetting techniques

A
  • work at room temperature
  • use correct pipette tips
  • use constant plunger pressure and speed
  • pull pipette straight out of any liquid
  • avoid handling the pipette tip
  • set the pipette down between samples
  • eject tip in to proper waste receptacle
38
Q

tips for small volume pipetting

A
  • insert pipette straight into the bottom of the tube
  • insert pipette tip into existing liquid

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