FS 160 Lecture Notes - Lecture 12: Partial Oxidation, Buccal Swab, Genotyping
FS 160 – Lecture 12 – Databases
I. No Suspect DNA Cases
a. Relies on victim testimony (memory) under duress
i. Most prone to wrongful conviction
b. Have suspect DNA present a substantial proportion of the time (seminal fluid)
c. Make use of available tools in the forensic DNA arsenal
i. Crime scene DNA
ii. Y STR
iii. DNA databases
d. No suspect cases are virtually unsolvable prior to the age of forensic DNA
II. Sexual Assault Victims
a. 366,460 sexual assaults are reported per year in the U.S. (1992-2000 average)
i. 1000 per day, 42 per hour, or one sexual assault reported every 86
seconds
b. Only 1/3 to 1/20 of sexual assaults are reported to police
i. This number is very conservative
III. Sexual Assaults by Strangers
a. 34% of sexual assaults are committed by a stranger
i. Termed a “no suspect” sexual assault, therefore these cases are normally
unsolved without DNA
IV. Recidivism (Repeat Offenders)
a. 2/3 of offenders are repeat offenders
b. Same offenders are committing the same crimes on new victims
V. Number of Offenses Per Offender
a. Average serial rapist commits 8 sexual assaults prior to apprehension
b. 7 offenses per serial sexual offender are now preventable with crime scene DNA
done on every case and a current DNA database
i. 8 offenses per serial sexual offender, minus the first offense to risk getting
caught
VI. Foreign DNA Profiles
a. 47.58% crime scene DNA success rate
i. % of cases where sperm is found and a male DNA profile is generated
VII. Solving Cases
a. 42% DNA database success rate
i. % of cases where a hit is made to a known offender
b. 69% if case to case hits are included
VIII. Cost of Crime
a. $111,238 cost of crime per offense committed
i. adjusted from 1995 study to 2003 dollars
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1. includes the physical injury, hospitalization, lost time at work,
counseling, and “pain and suffering”
2. no amount been added for cost of investigation, prosecution,
justice system, or incarceration
IX. Putting Pieces Together
a. 124,596 reported “no suspect” sexual assaults
b. 83,056 of no suspect sexual assaults are committed by repeat offenders
c. 581,392 future sexual assaults that are preventable
d. 276,626 unnecessary victims of preventable sexual assaults
e. 116,183 estimated sexual assaults solved
f. $12.9 billion saved cost
g. Expense to do cases = $366 million
h. Return on investment (ROI) = over $35 saved for every dollar spent
i. Database cost is a one-time cost in establishing
1. Only need one sample per suspect per lifetime
X. Steps in DNA Analysis
a. Collection
b. Extraction
c. Quantitation
d. Genotyping
e. Interpretation of results
f. Database
i. CODIS: Combined DNA Index System
1. Used for linking serial crimes and unsolved cases with repeat
offenders
2. Convicted offender and forensic case samples
3. Launched October 1998
4. Requires 13 core STR markers
5. Annual results with NIST SRM required for submission of data to
CODIS
6. No names are associated with DNA profiles uploaded in the
National DNA Index System (NDIS)
XI. Database vs. Databank
a. database: collection of computer files containing entries of DNA profiles that can
be searched to look for potential matches
b. databank: collection of actual samples
i. Usually in form of a blood sample or buccal swab or DNA extracts
XII. Sample Retention
a. Most jurisdictions permit retention of biological specimen even after STR typing
results have been obtained and the DNA profile is entered into database
b. Sample retention is for quality control purposes and enables testing of additional
STRs or other genetic loci should a new technology be developed in the future
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Document Summary
Sexual assaults by strangers: 34% of sexual assaults are committed by a stranger, termed a no suspect sexual assault, therefore these cases are normally unsolved without dna. Foreign dna profiles: 47. 58% crime scene dna success rate, % of cases where sperm is found and a male dna profile is generated. Vii: 42% dna database success rate, % of cases where a hit is made to a known offender, 69% if case to case hits are included. Codis: no names are associated with dna profiles uploaded in the. Sample retention: most jurisdictions permit retention of biological specimen even after str typing results have been obtained and the dna profile is entered into database, sample retention is for quality control purposes and enables testing of additional. Strs or other genetic loci should a new technology be developed in the future: hit confirmation. Aspects of a national dna database: commitment on part of each state and local government to provide samples for.
