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Presentation to Manchester College\'s Science Department; describes the legal aspects of forensic science in a trial presented by my elected prosecutor, Curtis Hill, and chief deputy, Vicki Becker.
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STATE V. MOTT: A CASE STUDY
IN FORENSIC SCIENCEGraham Polando
Deputy Prosecuting AttorneyElkhart County, Indiana
Elkhart County YMCA
Kari’s Family’s CarFound at 1527 Morton Ave.; Jan. 30, 1991
Kari is Found: February 5, 1991
Bonneyville Mill County Park Dwight Miller’s In-Court Testimony
Q: And what was it that you saw?
A: The nude body of a female…I immediately jumped out of the truck….and as I went around the front of the truck, I started yelling Kari’s name….just screaming it out, I think, more than anything, to get a response or whatever…
The Autopsy: Dr. Rick Hoover
Forensic Pathologist for South Bend Medical Foundation
B.S., Biochemistry, Manchester College
M.D., Indiana University School of Medicine
1,200 Autopsies in 26 Years of Practice
Dr. Hoover’s Findings
•Prolonged Cold Environment Exposure•Soft tissue damage to lips and cheek•Blunt Trauma Injury to Head•“The most significant injury she had was not really a direct injury, but it’s an anatomic marker…petechial hemorrhages around the periorbital area.”
Petechial Hemorrhages
“Marker” Injury
Eyes and Neck
Suddenly stop But no abrasions
Sexual Assault Examination
Physical examination of each orifice
Swabs are used in each orifice to create slides for staining Extracts both skin and fluids
In-Court Testimony onCause of Death
“It would be my opinion that [Kari] died as a result of asphyxia due to cervical compression and secondarily to vaginal injuries.”
“My opinion is Kari’s death is a homicide.”
Limitations on the Investigation
Primitive Available Testing: Blood Group Testing (Type) Lab Technician: “Spermatozoa were observed on the
vaginal smear slides…” Restriction Fragment Length Polymorphism (RFLP)
Mary Reed, Forensic Biology Supervisor for the Indiana State Police: “I would have consumed or used up the entire standard…
in an attempt to get a profile.” “There would be new extraction processes and also new
technologies on the horizon…”
Police investigation ends later in 1991 with no arrests
DNA Analysis since Kari’s Death
Polymerase Chain Reaction (PCR)
Short Tandem Repeat (STR)
Mitochondrial DNA (mtDNA)
Y-Chromosome Analysis
Polymerase Chain Reaction (PCR)
Replicates DNA from even small amounts of biological material Likewise replicates contaminants
Short Tandem Repeats (STR)
Nuclear DNA Polymorphic Loci Nucleotides repeat Result is number of
repeats Produces two numbers:
one from each chromosome
Warming the Cold Case
Evidence sits in Elkhart Police Department storage locker until 2005
Elkhart County Sheriff Mike Books refers case to Indiana State Police Cold Case Unit
Thomas Littlefield, ISP
Cold Case Specialist Noted Advances in DNA
Analysis Starts with…
Fred Mott
Train tracks encounter 1527 Morton Avenue
connection Female screams from
apartment Carrying object
“wrapped up like a carpet”
Loan application Fled Large amounts of
plastic
Fred Mott, California State Prisoner P19833
California State Prison, Lancaster Serving Life Sentence
for 1998 Rape of UC-Berkeley Student
Unclear: Warrant or Consent?
Federal Express shipped from South Bend airport to Reliagene Technologies (now Orchid Cellmark)
Reliagene (Now Orchid Cellmark)
Why a private laboratory? Competent
FQS-I Accredited Quick Objective Admissible Hearsay
What Reliagene Had
What Reliagene Did
8-Loci Reliagene ProfileMini-STR Results
Locus
07-05734
Generic Sample from
Kari
07-05735.01
Vaginal Epithelial Cells
07-05735.02
Sperm Isolated from Vaginal
Epithelial Cells
03-14372
Blood from Fred Mott in California
D8S1179 13,16 13,16 NR 10,14D21S11 29,30 29,30 30 29,31.2D7S820 10,11 10,11 8,9 8,9CSF1PO 12 12 7,10,12 7,10
D3S1358 15,18 15,18 NR 15,17TH01 6,9.3 6,9.3 NR 7,8
D13S317 8,12 8,12 12 12D16S539 10,13 10,13 [10],11,13 11,13D2S1338 20,23 20,23 [20],23,24,25 24,25D19S433 13,14 13,14 NR 11,16.2
vWA 16,17 16,17 NR 15,17TPOX 9,11 9,11 NR 8,9
D18S51 15,17 15,17 14,15,19 14,19AMEL X X X,[Y] X,Y
D5S818 12,13 12,13 NR 10,13FGA 20,22 20,22 [21],22 21
Ms. Nasir’s Conclusions
Q: “Is the profile on the sperm fraction…the same as that from the blood sample of Fred Mott?”
A: “Yes. The profile obtained from the sperm fraction…are [sic] consistent with Fred Mott’s DNA sample. So therefore, Fred Mott is not excluded as a DNA Donor in the sperm fraction.”
Q: “You use the term, ‘not excluded.’ What does that mean?...”
Role of Probabilities
Different Profiles: Individual could not have contributed
Identical Profiles: Individual could be an “exact match” or simply “cannot be excluded.”
“Exact Match” vs. “Cannot be excluded”: Exact Match must:
Be single source and exceed 1 in 5.9 trillion
Cannot be excluded: will produce probability > 1 in 5.9 trillion
Ms. Nasir’s Probabilities
“For this sample, the probability of someone having any possible combination of this profile is 1 in 862,000 individuals of Caucasian descent,
and 1 in 546,000 individuals of African-American
descent.”
Are these probabilities of innocence?...
The Prosecutor’s Argument
“And then we have the DNA analysis. [Defense counsel] would lead you to believe that because they say it’s not a match, that’s not good enough. But, again, you were here; you observed; the evidence was quite clear. The only time we talk about a match is when it’s 5.9 trillion. That’s impossible…”
The Prosecutor’s Argument
“…There’s [sic] six billion people on earth. That would mean one thousand times more people on earth is when they can say it’s a match. That’s because it’s science, ladies and gentlemen. And science has to have their statistics. But you don’t have to worry about that, because as we’ve explained, this hooks up to the facts. And as you see the DNA profiles, it was Fred Mott.”
Appellate Issue: Prosecutorial Misconduct “Mott claims this is a misstatement of the evidence
because ‘[t]here could be a DNA “match” even if there were far fewer people on the Earth.’”
Indiana Court of AppealsMott v. State
“The evidence established that Mott was not excluded as a contributor and
that the probability of someone having any possible combination of the relevant DNA profile was: 1 in 862,000 individuals of Caucasian descent
and 1 in 546,000 individuals of African-American
descent.”
Indiana Court of AppealsMott v. State
“The prosecutor did not overstate the significance of the DNA evidence, which constituted substantial evidence of Mott’s guilt.”
The Prosecutor’s Fallacy?
Thompson, W. & Schumann, E. (1987). Interpretation of Statistical Evidence in Criminal Trials: The Prosecutor’s Fallacy and the Defense Attorney’s Fallacy. LAW AND HUMAN BEHAVIOR 11(3), Sept. 1987, pp. 167-187.
The Prosecutor’s Fallacy?
Thompson and Schumann: Saw a jury trial in which Defendant (known)
and Perpetrator (unknown) shared a blood type common to 10% of the population
Prosecutor: “90% chance Defendant is perpetrator”
Thompson and Schumann’s Hypothetical
All lawyers own briefcases.
One in ten people in the general population own a briefcase.
Jim owns a briefcase. What is the probability
Jim is a lawyer?
Answer
90%?
What are the relative numbers of lawyers and non-lawyers in the population?
Thompson and Schumann: “To draw conclusions about the probability a criminal suspect is guilty based on evidence of a ‘match,’ we must consider not just the percentage of people who would match but also the a priori likelihood that the defendant in question is guilty” (p. 170).
Bayes’ Theorem
Jury: “25% chance Defendant is guilty”
New evidence: Hair found at crime
scene matches only 1% of population
Defendant member of that 1%
97% guilty, not 99% Prosecutor’s
Argument: “This hooks up to the facts.”
Broun, K., Mosteller, R., and Giannelli, P. (2002) EVIDENCE: CASES AND MATERIALS (6th Ed.) (citing Finkelstein & Fairley, 1970).
Guilty
“Rapist, not a killer” 60 Years in the Indiana
Department of Correction, Consecutive to California Sentences
ELKHART COUNTY COURTHOUSE
REFERENCES
Broun, K., Mosteller, R., and Giannelli, P. (2002) EVIDENCE: CASES AND MATERIALS (6th Ed.) St. Paul, MN: Thompson West.
Mott v. State (Ind. Ct. App. 11/13/08) (unpublished disposition).
United States Department of Justice (2002). “Using DNA to Solve Cold Cases.” Available online at http://www.ojp.usdoj.gov/nij/pubs-sum/194197.htm.
Special Thanks
Kenneth R. Martin, Esq., Goshen, Indiana
Curtis T. Hill, Elkhart County Prosecuting Attorney
Vicki E. Becker, Elkhart County Chief Deputy Prosecuting Attorney
Orchid Cellmark, Inc.
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