Forensic Identity Claims

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Human Identity

Forensic Identification

•Organisms can be easily identified through it’s unique DNA sequence

•Our DNA plays an important role in our everyday life from our genealogy to court•We could easily profile someone’s identity through the use of DNA•Forensic scientist use a special scanner to view thirteen areas of the DNA

•DNA pattern produces a particular DNA profile for that Person

•DNA profiles are known as DNA fingerprints

History of DNA Testing

•Sir Alec Jeffreys & DNA Finger Print History  

•   professor and geneticist at the University of Leicester in the United Kingdom (UK) and pioneered DNA-based identity testing  

• Interested in studying the genetic variation between individuals

• Analysis of the myoglobin gene in seal meat

•   Found short repeating sequences that were homologous between humans and seals

•  Repeating sequences “could be highly variable, informative genetic markers”

• developed a radioactive probe, made up of short sequences, that could latch onto those repeating sequences and ultimately reveal patterns that were unique to each individual: a DNA “fingerprint”

DNA Profiling• DNA Profiling or Short Tandem Repeat(STR) Analysis

• Powerful tool in forensic investigation

• Uses the method of short DNA Fragments

• DNA Fragments are usually measured under fluorescent labels in order to see if the sample matches

• DNA profiling is simply the collection of VNTR, or the unique sequences on the loci

• VNTR: Variable Number Tandem Repeats

• Most DNA sequences in different people look too similar to tell apart. After processing, however, VNTRs result in bands that are unique enough to be used for identification.

• Ways to profile: Genetic Finger Printing and Gel Electrophoresis

Genetic Finger Printing

• Collection of sample: scientist only need a tiny amount of DNA

• Amplification of tell tale regions: Technique of Polymerase Chain Reaction (PCR). Makes millions of copies of the telltale region of the sample. The telltale region is the number of repeat bases it contains or the Short Tandem Repeat (STR).

• Count repeats: dyes are attached to the STR copies, one dye for each region in order for the regions to be distinguished in the mix

• Look for matches: To convict a suspect the STR repeats must match the repeats in the crime scene sample

Gel Electrophoresis in Forensic Science

•Gel electrophoresis is a method that separates and view DNA, RNA, and proteins

• Is a technique used in forensic science to analyze DNA samples

•A person’s DNA is unique, the pattern of separation in the gel will be different for each person

•During a crime investigation this technique is used to determine if the two samples are a match

Basic Procedure 1.Preparation of the gel

(usually agarose)

2.Holes are put into the gel to hold the DNA solution

3.Scientist places DNA solution in the gel and applies an electrical current

4.DNA moves due to the electric current and migrates through the gel

5.The smaller DNA moves through the gel faster than larger pieces

Special Cases A.      30-Year-Old Murder Solved

CASE: 61- yr old Carroll Bonnet was stabbed to death in his apartment. . Police collected evidence, including latent fingerprints and palm prints from the victim’s bathroom (officers believed the killer was trying to wash off blood and other evidence before leaving the apartment). The victim’s car was then stolen.

INVESTIGATION:The car was on Illinois but after print collection, no new clues were found. There were no matches in the fingerprints.RE-INVESTIGATION  2008: Laura Casey searched for the prints in IAFIS (did not exist in 1978). She found a positive identification to Jerry Watson.

B.       The Murder of Leanne Tiernan

  CASE: In August 2001, a man walking his dog in Lindley Woods, near Otley, in West Yorkshire, found the body of 16-year old Leanne Tiernan, buried in a shallow grave. This was about ten miles from her home in Landseer Mount, Bramley, Leeds. She had been walking home from a Christmas shopping trip with her best friend in November 2000 when she disappeared

 THE SCENE:

o   Plastic bag on head

o   Dog collar

o   Scarf in neck

o   Cable tie in wrists

o   Green plastic around her body

 INVESTIGATION:

o   Searched for the suppliers of dog collar and the twine

o   Found out about John Taylor

 DNA EXAMINATION

o    Hairs found in the scarf

C.     A twist of fate

 CASE: A fifteen year old school girl, Lynda Mann was abducted in Narbourough,

England. The next day, her body was discovered raped and murdered.  Three years later,

another young woman met the same fate near Lynda’s resting place

 INVESTIGATION:

o    Richard Buckland admitted the second crime but not the first one

o    He undergone DNA analysis (genetic fingerprinting) but it did not match

o    5,500 men were tested around the area until a guy named Colin Pitchfork

was arrested

Role of forensics in Identity

• DNA forensic identification allows a potential suspect to be identified

• Evidence in the crime scene is crucial particularly when it involves DNA

• Also important in identifying victims of crime who are unrecognizable

• Establishes a familial connection in paternity cases

• Can link organ donors to those patients in need and can reduce immunological rejection

Elvidge, S., (2015). Forensic cases: the murder of leanne tiernan. retrieved from http://www.exploreforensics.co.uk/forensic-cases-murder-leanne-tiernan.html

Filter, D.,(2013).5 Real-life cases where DNA profiling changed everything. retrieved from http://forensicoutreach.com/5-real-life-cases-where-dna-profiling-changed-everything/

Saad, R., (2005). Discovery, development, and current applications of DNA identity testing. pp130-133. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1200713/.

The FBI Stories. (2012).30-year-old murder solved: fingerprint technology played key role. retrieved from http://www.fbi.gov/news/stories/2012/september/30-year-old-murder-solved

nsics and Human Identification." GE Healthcare Life Sciences. N.p., n.d. Web. 26 Feb. 2015.

Freeman, Shanna. "How DNA Profiling Works." HowStuffWorks. HowStuffWorks.com, n.d. Web. 26 Feb. 2015.

"How DNA Profiling Works." Grow Wisconsins Magazine for the Life Sciences. N.p., 15 Feb. 2011. Web. 25 Feb. 2015.

Murnaghan, Ian. "Understanding Forensic Identification." Understanding Forensic Identification. N.p., 20 Aug. 2014. Web. 26 Feb. 2015.

Wiley, Carol. "How Is Gel Electrophoresis Used in Forensic Science? Read More : Http://www.ehow.com/about_6463741_gel-electrophoresis-

used-forensic-science_.html." HowStuffWorks. HowStuffWorks.com, n.d. Web. 26 Feb. 2015.

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