Mitochondrial Analysis From Hair Examinations to DNA Sequencing

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Mitochondrial Analysis From Hair Examinations to
DNA Sequencing

• State of Connecticut
• Forensic Laboratory

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Trace Evidence

• Trace evidence items or debris found in the
  process of investigating a crime
• Generally small in size, may be transferred when
  physical contact occurs between two individuals
  or an individual and an object.
• Hairs a commonly encountered example of trace
  evidence.

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Hair

• A biological outgrowth from the skin of mammals.
• Three areas of a hair Root, Shaft, Tip
• Three cross-sectional regions of a hair Cuticle,
  Cortex, Medulla

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Hair Evidence

• Found in many crimes, submitted to the
  laboratory.
• Can include homicides, hit and runs, sexual
  assaults, kidnappings, burglaries, etc.
• Can associate a suspect to a victim, weapon
  and/or a crime scene.

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Why Is Hair Good Evidence?

• Abundant the average person has 100,000 hair
  follicles on their head alone
• Easily transferable the average person loses 100
  hairs per day
• Considerable variability comparing body area
  alone, human hair can be from the head, pubic,
  anal, eye, nose, ear, underarm, leg, arm, chest,
  trunk, or beard area, not including the fine hair
  covering the entire body except on a persons
  palms and soles.
• Durable hairs have been recovered from mummies
  dating back 2,000 years

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Steps of Analysis

• Hairs are collected from evidence submitted
• Hairs are identified and preserved onto glass
  microscope slides
• Hairs are examined both macroscopically and
  microscopically
• If a known standard exists, hairs are compared
• A report containing all the results of the
  comparison is written
• Examiner testifies in a court of law to the
  results written in the report.

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Processing

• Type of evidence submitted is anything on which a
  hair could possibly be found includes clothing,
  letters, guns, knives, bomb devices, bedding, car
  parts, furniture, carpets, flooring, tape, etc.
• Hairs are collected by either scraping, picking,
  taping or vacuuming.

• Hairs are identified from the
• collected debris and mounted onto glass
  microscope slides

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Examination

• Macroscopic characteristics of hair length,
  coloration, shaft shape, and texture.
• Microscopic characteristics of hair include
• The hair shaft (optical cross section, diameter
  variation, tip appearance, buckling, artifacts,
  other)
• The cuticle (thickness, appearance, color,
  damage)
• The cortex color, pigment granule size, pigment
  granule shape, pigment granule distribution,
  pigment granule density, cortical inclusions,
  cortical fusi (size, distribution, and density),
  ovoid bodies (size, distribution, and density),
  cortical texture
• The medulla (color, thickness, texture,
  continuity pattern, abnormalities)
• The hair root (condition, color, tissue, cortical
  fusi)

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Results

• A qualified hair examiner can provide the
  following information
• from a hair examination and comparison
• 1. Whether there is hair(s) recovered from the
  item(s) submitted.
• 2. What the racial origin of the hair is
  (Caucasian-type, Negroid-type, Mongoloid-type)
• 3. The area of the body that the hair came from
  (head, pubic, body)
• 4. The nature of the hairs removal from the
  body
• 5. Whether the hair has been artificially
  treated
• 6. Whether there has been damage done to the
  hair
• 7. Whether there are similarities and/or
  differences between the questioned hair and known
  sample.
• How much information an examiner can provide
  depends upon the suitability of the hair.

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Hair Examination Conclusions

• A hair examiner can conclude the following
• 1. The questioned hair exhibits similar
  characteristics (no significant differences are
  present) to the known sample. Thus, the source
  of the known sample cannot be excluded as being
  the source of the questioned hair.
• 2. The questioned hair exhibits dissimilar
  characteristics to the known sample. Thus, the
  source of the known sample can be excluded as
  being the source of the questioned hair.
• 3. The questioned hair exhibits both
  similarities and differences to the known sample.
  Thus, no conclusion can be reached as to whether
  the questioned hair can or cannot be excluded as
  coming from the same source as the known sample.
• 4. The known hairs are insufficient or
  unsuitable for comparison purposes.
• 5. The questioned hair(s) are insufficient or
  unsuitable for comparison purposes.

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Further Testing A Complement To Forensic Hair
Examinations

• Hair examinations can not identify a specific
  individual
• Results can be supplemented by performing other
  independent analyses
• Further testing will not change conclusions
  stated by the hair examiner
• Can provide alternative and additional
  information about the hair Further testing is
  deemed suitable and/or probative based upon
• If the hair root has tissue attached, Nuclear DNA
  analysis
• If there is no tissue and/or root, Mitochondrial
  DNA analysis

Nuclear DNA
Mitochondrial DNA
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Mitochondrial DNA Analysis

• Mitochondria are considered the powerhouse of
  the cell
• Where the energy to run cellular functions (ATP)
  is made
• Has its own DNA (mtDNA)

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Nuclear DNA vs. Mitochondrial DNA

• NUCLEAR DNA
• Linear
• 2 Copies per cell
• Very large (3 billion base pairs)
• Inherited from both parents
• Unique to the individual (except identical twins)

• MITOCHONDRIAL DNA
• Circular
• Thousands of copies per cell
• Small (Just over 16,000 base pairs)
• Inherited only from the mother
• Not unique

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When Would We Use Mitochondrial DNA?

• Hairs missing the Root
• Old Bones, Teeth
• Missing persons cases
• Mass Disasters
• Since mitochondrial DNA has a high copy number,
  it is more resistant to degradation

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Why Isnt Mitochondrial DNA Unique?
Mother
All Yellow Same mtDNA type as Mother
Female
Male
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How Is Mitochondrial Testing Done

• Extraction of DNA from sample
• Amplification of extracted DNA, to make many
  exact copies of the DNA we extracted
• Quantitation of amplified DNA, to determine how
  much DNA is there
• Determine the sequence of two specific regions of
  the mitochondrial genome

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Now What?

• Compare sequences of questioned items to known
  sequences
• Are they different?

Case 1 Case 2 Questioned GCATATTGCGCCTA
GCATATTGCGCCTA Known GCACATTACGTCTA
GCATATTGCGCCTA EXCLUSION CANNOT
EXCLUDE
This is a simplification, the regions
scrutinized are larger, and analysis is far more
complicated. This is meant to assist in a very
basic understanding.
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And Last

• Compare the attained sequence with the
  Mitochondrial CODIS Database
• How many times does the sequence weve attained
  appear in the database
• From that number, we can estimate the frequency
  of that sequence in the general population

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Interesting Forensic Casework Involving
Mitochondrial DNA

• Tsar Nicholas II Romanov
• Did we find Anastasia?
• NO
• Anna Alexander claimed to be the missing child of
  Nicholas Romanov
• Her mitochondrial DNA did not match those of
  unearthed bones, or of maternal relative Philip
  of Edinburg

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Interesting Forensic Casework Involving
Mitochondrial DNA

• Tennessee Vs. Ware
• First case in US where mitochondrial testing was
  introduced.
• September, 1996
• Murder case in which the only evidence found was
  red hairs in throat of victim and on the victims
  bed
• Paul Ware could not be excluded as the source of
  the hairs.

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Interesting Forensic Casework Involving
Mitochondrial DNA

• Connecticut Vs. Pappas
• Robbery, first CT case in which mitochondrial DNA
  analysis was allowed in the courts
• Mitochondrial DNA analysis on two head hairs from
  sweatshirt found on train tracks adjacent to
  where some of the robbed money was located
• The defendant could not be excluded as the source
  of the questioned hair sample
• Case appealed up to CT Supreme Court, who ruled
  that this type of testing is acceptable

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Interesting Forensic Casework Involving
Mitochondrial DNA

• Connecticut Vs. Torres
• Murder/Sexual Assault, verdict March, 2002
• Amount of DNA recovered not sufficient for
  nuclear DNA testing
• Mitochondrial profile from semen matched that of
  the suspect
• For more detail on this case, click here to see
  description from the laboratorys trace section,
  who had a major contribution to the outcome.