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FSC402HFORENSIC SCIENCE AND THE EXPERT
December 2, 2003
Forensic Issues
Continuity
Quality Assurance
Accreditation
Expert Testimony
Continuity
Continuity, Chain of Custody
The procedures in place that account for the integrity, identification, and security of each specimen by tracking its handling and
storage from its receipt to final disposition.
Continuity
Seals Secure Identity
Security In transit In storage
Receipt
Disposition
Continuity
Seals Secure
Prevents tampering of the item Provides a unique identifier of the item
Identity Provides a unique identifier of the item
Continuity
Security In transit
transferred from site to site by a staff member transfer between areas (eg. CRO to toxicology) is from staff member to staff member
In storage locked rooms sealed containers
Continuity
Receipt
* Record all information*
signs of tampering
item type, seal type, identifier #, attribution
initiate chain of custody
dates
initials
placement of integrity seals if not present
Continuity
Disposition
disposal – biological samples
return to submitter – non-biologicals
under secure seal
* MUST BE RECORDED
Quality Assurance
Quality Assurance
Those planned and systematic actions necessary to provide sufficient confidence that a laboratory's product or service will satisfy given
requirements for quality.
Lab wide
Whole system
Quality Assurance
Quality Control
Internal activities or activities according to externally established standards used to monitor the
quality of analytical data and to ensure that it satisfies specified criteria.
e.g. quality control standard – a standard of known concentration to be tested in the method in
question
may be internal or external
Quality Assurance
Includes: Use of validated procedures
Review of all results and reports technical administrative
Accreditation
Continuing Education
Quality Assurance
Includes: Use of proficiency testing
Comparative testing - analytical Internal quality control samples - analytical External quality control samples - analytical Evaluation of Scientist
expert testimony evaluation of reports
Quality Assurance
Validation of Technical Procedures
Quantitative Procedures Qualitative Procedures- specificity - specificity- accuracy- precision- linear range- limit of quantitation- limit of detection - limit of detection- ruggedness - ruggedness
Quality Assurance
Specificity
ability to measure analyte in the presence of other compounds expected to be found in the matrix
Ruggedness
can the method be duplicated different days different individuals
Quality Assurance
Accuracy
closeness to the true value or expected value
Precision
closeness to each other
Quality Assurance
Limit of Quantification lowest value accurately and precisely measured
Limit of Detection lowest value that can be distinguished from from
background
Linear Range range over which standard curve is accurately and
precisely linear
Accreditation
PURPOSE
To demonstrate that an organization has policies in place to
Assure qualityDetect deficiencies
Take corrective action
Accreditation
PURPOSE
To demonstrate that an organization’s management, operations, personnel, procedures,
equipment, physical plant, security and health and safety procedures meet established standards
Accreditation
SAY WHAT YOU DO
DO WHAT YOU SAY
Accreditation
ASCLD/LAB
American Society of Crime Laboratory Directors
Laboratory Accreditation Board
Accreditation
100% Essential e.g. written or secure electronic chain of custody
70% Important e.g. existence of a quality manual
50% Desired e.g. general cleanliness/good housekeeping
The Expert Witness