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DNA Analysis

Intro to DNA analysis - methods, history, legality and case studies.

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DNA Analysis

  1. 1. <ul><li>Jasmine Stewart </li></ul><ul><li>Katherine Sweetin </li></ul><ul><li>AJ Ojo </li></ul><ul><li>Ashley Miller </li></ul><ul><li>Yosok Pun </li></ul><ul><li>Amber Dawkins </li></ul>DNA Analysis
  2. 2. <ul><li>Introduction to DNA Analysis </li></ul>
  3. 3. What is DNA analysis? <ul><li>DNA analysis is an examination method that emerged in the mid 1980’s by Alec Jefferys, an English geneticist. </li></ul>
  4. 4. How Does it work? <ul><li>Any organism can be identified by examination of DNA sequences unique to the specific species. </li></ul><ul><li>To identify individuals, forensic scientist scan 13 DNA regions (loci) and create a DNA profile for that individual (DNA finger print) </li></ul><ul><li>There’s a very slim chance that another individual has the same DNA profile for a specific set of 13 loci's. </li></ul>
  5. 5. How is DNA typing done? <ul><li>Only 1/10 of a single percent of DNA (about 3 million base pairs) differs between individuals. </li></ul><ul><li>Scientist use these regions to generate a DNA profile of an individual using samples from blood, bone, and hair. </li></ul><ul><li>In criminal cases, samples are collected from the crime scene evidence, and a suspect, extracting DNA and analyzing it for a set of specific DNA markers </li></ul><ul><li>Markers are found in DNA by making small pieces of DNA (probes) that will seek out and bind to a complementary DNA sequence in the sample </li></ul>
  6. 6. DNA Typing Cont’d <ul><li>The DNA profiles are then compared to determine if the suspect sample matches the evidence sample </li></ul><ul><li>If the sample profiles do not match, the suspect was not part of the crime </li></ul><ul><li>If the patterns match the suspect most likely was a part of the crime </li></ul><ul><li>The more probes used in DNA analysis , the greater the odds for a unique pattern and definite match. Four to six probes are recommended. </li></ul>
  7. 7. Effectiveness of DNA <ul><li>DNA Identification is quite effective when used correctly. </li></ul><ul><li>Portions of DNA sequence that vary the most among humans MUST be used </li></ul><ul><li>Portions must also be large enough to factor in the fact that human mating is not absolutely random </li></ul>
  8. 8. Examples of use of DNA In forensics <ul><li>Identify potential suspects whose DNA may match evidence left at crime scene </li></ul><ul><li>Exonerate persons wrongly accused of crimes </li></ul><ul><li>Identify crime and catastrophe victims </li></ul><ul><li>Establish paternity and other family relationships </li></ul>
  9. 9. DNA Technology <ul><li>CODIS, which stands for Combined DNA Index System, is a program which consists of many databases that have DNA profiles useful for the criminal justice system </li></ul><ul><li>The NDIS, or National DNA Index System, is the part of CODIS that contains the DNA profile at a national, state, and local level and is accessible to law enforcement all over the country </li></ul>
  10. 10. DNA Technology <ul><li>The DNA types stored in this system consist of stretches of a chromosome that are highly variable between individuals. These are usually STR tetramers, or a sequence of four nucleotides which repeats many times. </li></ul>
  11. 11. DNA as Evidence <ul><li>DNA is easily contaminated due to the sensitivity and fragility of samples </li></ul><ul><li>Must be recognized that the issue of DNA contamination was not fully understood in the past, older cases may be linked to samples which could yield misleading results </li></ul><ul><li>Many guidelines for handling DNA samples within the lab before, during, and after processing </li></ul>
  12. 12. DNA as Evidence <ul><li>Degradation is also a common concern with DNA samples </li></ul><ul><li>Collection and storage must be carefully monitored to prevent bacteria growth </li></ul><ul><li>Evidence collected for the purpose of blood type testing may be stored according to that type of test and may limit chances of testing DNA in the sample </li></ul><ul><li>In some cases, DNA has been successfully extracted and analyzed from a moldy sample with the help of PCR technology </li></ul>
  13. 13. Laws related to DNA Technology <ul><li>With the recent advancements in DNA, many laws have been issued in regards to testing and use </li></ul><ul><li>Although DNA samples can last many years, and sometimes even decades, statutes of limitation are in place and vary state to state </li></ul><ul><li>A statute of limitation limits the amount of time between a crime and a conviction </li></ul><ul><li>Many law makers are now realizing that theses statutes of limitation are becoming obsolete due to the reliability of a properly stored DNA sample </li></ul>
  14. 14. Laws Related to DNA Technology <ul><li>With the realization that DNA databases lead to convictions, laws were put in place to ensure their continued success </li></ul><ul><li>All states require at least some convicted offenders to provide a DNA sample to incorporate their profile into the database </li></ul><ul><li>Federal government now requires samples from those convicted of Federal or military crimes </li></ul>
  15. 15. Equipment for DNA Analysis <ul><li>Thermocycler- also known as a thermal cycler, it is used to amplify segments of DNA via PCR </li></ul><ul><li>ABI 310 Genetic Analyzer- used for STR genotyping </li></ul>
  16. 16. <ul><li>DNA Techniques </li></ul>
  17. 17. <ul><li>DNA analysis consists of traditional and specialized techniques. </li></ul><ul><ul><li>Traditional Techniques: Restriction fragment length polymorphism (RFLP), and short tandem repeat (STR) analysis. </li></ul></ul><ul><ul><li>Specialized Techniques : mitochondrial DNA (mtDNA) analysis, Y-marker analysis, single nucleotide polymorphism, or SNP. </li></ul></ul>http://ec.europa.eu/dgs/jrc/index.cfm?id=1410&obj_id=7360&dt_code=nws&lang=en http://theamazingworldofpsychiatry.wordpress.com/2010/07/05/review-the-genetics-of-alzheimers-disease-and-frontotemporal-dementia/
  18. 18. (RFLP) Restriction fragment length polymorphism http://www.austincc.edu/mlt/mdfund/mdfund_unit13objectives.html http://www.bio.davidson.edu/COURSES/genomics/method/RFLP.html
  19. 20. Now What? <ul><li>Now compare questioned sequence to known sequence. </li></ul>Suspect #1 Suspect #2 Q uestioned GCA T ATT G CG C CTA GCATATTGCGCCTA K nown GCA C ATT A CG T CTA GCATATTGCGCCTA *Exclusion *Inclusion (No Match) (Match) www.ct.gov/dps/lib/dps/​Mitochondrial.pdf.ppt Suspect Object Scene Victim
  20. 21. <ul><li>DNA Matching History, Collection and Databases </li></ul>
  21. 22. Brief History of DNA Matching <ul><li>1970s – HLA Testing </li></ul><ul><li>HLA inherited from both parents. Used for paternity testing and biological relationships . High exclusion rate of 80% </li></ul><ul><li>1980s- DNA Testing Using RFLP Technique </li></ul><ul><li>First genetic test using DNA. Higher exclusion rate of 99.99% </li></ul><ul><li>1990s - DNA Testing Using PCR Technology </li></ul><ul><li>DNA tests made more easy and quick </li></ul><ul><li>2007s and beyond – Ancestry Research </li></ul><ul><li>Y-STR and mtDNA used for male and female line respectively </li></ul>
  22. 23. Admissibility of DNA Evidence In American Courts <ul><li>November, 1987 - Tommy Lee Andrews was one of the firsts convicted using DNA tests. Rape Conviction </li></ul><ul><li>State v. Woodall – West Virginia Supreme Court first high court to rule on the admissibility of DNA evidence </li></ul><ul><li>People vs. Castro – Court certifications, accreditations and standardization guidelines were established (Chain of Custody in Courts) </li></ul>
  23. 25. Chain of Custody <ul><li>Used to make sure DNA samples is not contaminated. Proper paperwork required for court proceedings </li></ul><ul><li>DNA collected by third party laboratory professionals. </li></ul><ul><li>Gloves are worn and caution is observed </li></ul><ul><li>DNA is collected and sealed in a specially made package </li></ul><ul><li>Receiving lab will first check to make sure the package is sealed before proceeding to work on the DNA </li></ul>
  24. 26. DNA Collection <ul><li>A weapon, such as a baseball bat, fireplace poker or knife, which could contain sweat, skin, blood or other tissue </li></ul><ul><li>A hat or mask, which could contain sweat, hair or dandruff </li></ul><ul><li>A facial tissue or cotton swab, which could contain mucus, sweat, blood or earwax </li></ul><ul><li>A toothpick, cigarette butt, bottle or postage stamp, all of which could contain saliva </li></ul><ul><li>A used condom, which could contain semen or vaginal or rectal cells </li></ul><ul><li>Bed linens, which could contain sweat, hair, blood or semen </li></ul><ul><li>A fingernail or partial fingernail, which could contain scraped-off </li></ul>
  25. 27. DNA Matching <ul><li>1.Inclusions, in which the suspect DNA matches that of the DNA profile taken from the crime scene. </li></ul><ul><li>2.Exclusions, in which the suspect DNA does not match that of the DNA profile taken from the crime scene. </li></ul><ul><li>3.Inconclusive results, results from possible contamination of evidence, and or DNA may be very small or degraded and cannot produce an accurate DNA profile. </li></ul>
  26. 28. Exoneration
  27. 29. Exoneration <ul><li>A person previously convicted of a crime is later found to be innocent of that crime (Wikipedia.org) </li></ul><ul><li>DNA testing of evidence has become the most common method of post conviction exoneration of the wrongfully accused. </li></ul><ul><li>In the first 225 DNA evidence exonerations, 77% of the exonerated persons were convicted due to eyewitness misidentification (Innocent Project). </li></ul><ul><li>Most of the exonerated persons were convicted of rape and sexual assault (Convicted By Juries, Exonerated By Science: Case Studies in the Use of DNA Evidence To Establish Innocence After Trial, 1996). </li></ul>
  28. 30. Common Causes of wrongful conviction <ul><li>Eyewitness misidentification </li></ul><ul><li>Invalid or improper forensic science </li></ul><ul><li>False confessions </li></ul><ul><li>Government misconduct </li></ul><ul><li>Informants / snitches </li></ul><ul><li>Bad lawyering </li></ul>
  29. 31. David Vasquez <ul><li>The first convicted defendant to be exonerated by DNA evidence testing in 1989 in Virginia </li></ul><ul><li>Wrongfully convicted of sexually assaulting and hanging a woman in her Arlington County, Virginia home and was sentenced to 35 years in prison </li></ul><ul><li>Convicted because two witnesses placed him near the scene of the crime (EYEWITNESS MISIDENTIFICATION), and he plead guilty because of he dreamt that he committed </li></ul>
  30. 32. David Vasquez cont’d <ul><li>Three laboratories conducted DNA testing on this case and other similar cases that involved the same sexual assault and murder methods that were used in this particular case and found the pubic hair from the scene of the crime inconclusive with Vasquez’s. </li></ul><ul><li>Exonerated in 1989 after having served 5 years of his sentence </li></ul><ul><li>( http://www.innocenceproject.org/Content/David_Vasquez.php and http://www.dna.gov/postconviction/convicted_exonerated/vasquez) </li></ul>
  31. 33. Kirk Bloodsworth <ul><li>The first convicted defendant exonerated from death row through post conviction DNA testing </li></ul><ul><li>Wrongfully convicted of the rape and brutal beating / murder of a 9 year old girl and sentenced to two consecutive life terms </li></ul><ul><li>Convicted because of an anonymous call and 5 eyewitnesses saying that Bloodsworth was seen with the girl earlier that day, a witness identifying him through a police sketch (EYEWITNESS MISIDENTIFICATION), and he admitted to doing something terrible that day, as well as mentioning a bloody rock </li></ul>
  32. 34. Kirk Bloodsworth cont’d <ul><li>Forensic Science Associates, the laboratory that conducted the DNA testing, performed Polymerase Chain Reaction (PCR) testing using reference blood samples from the victim and Bloodsworth. They found that the DNA from a semen stain found in the victim’s panties did not match any of the DNA collected from the samples, therefore Bloodsworth was excluded from this crime. </li></ul><ul><li>Exonerated in 1993 after having served almost 9 years of his double life sentence and spending 2 of those years on death row </li></ul><ul><li>( http://www.dna.gov/postconviction/convicted_exonerated/bloodsworth , http://towsonuniversity.worldcat.org/title/convicted-by-juries-exonerated-by-science-case-studies-in-the-use-of-dna-evidence-to-establish-innocence-after-trial/oclc/35089026/viewport , and http://www.dna.gov/postconviction/convicted_exonerated/bloodsworth) </li></ul>
  33. 35. DNA Data Bases <ul><li>The development and expansion of databases that contain DNA profiles at the local, State, and national levels have greatly enhanced law enforcement's ability to solve cases with DNA. </li></ul><ul><li>Convicted offender databases store hundreds of thousands of potential suspect DNA profiles, against which DNA profiles developed from crime scene evidence can be compared. </li></ul><ul><li>Given the recidivistic nature of many crimes a likelihood exists that the individual who committed the crime being investigated was convicted of a similar crime and already has his or her DNA profile in a DNA database that can be searched by the Combined DNA Index System (CODIS) software </li></ul><ul><li>In a typical month, the database churns out hits for 15 murders, 45 rapes and sexual offences and 2500 car, theft and drug crimes. With DNA evidence, the average crime cleanup rate increases from 24 per cent to 43 per cent </li></ul>
  34. 36. <ul><li>Case Study </li></ul>
  35. 37. Case Study: Familial DNA <ul><li>Familial searching is the use of family members' DNA to identify a closely related suspect in jurisdictions where large DNA databases exist, but no exact match has been found. </li></ul><ul><ul><ul><li>LA police arrested the serial killer “Grim Sleeper” </li></ul></ul></ul><ul><ul><ul><li>Accused of killing 11 people, dating back to 1985 </li></ul></ul></ul><ul><ul><ul><li>Compared DNA from crime scene with suspects son (in LA Lock-up ) </li></ul></ul></ul>Franklin had for a time, worked as a garage attendant at a Los Angeles police station and previously had an arrest record although his offenses did not require him to submit a DNA sample
  36. 38. Controversy <ul><li>Justice For All Act </li></ul><ul><ul><li>CODIS was once reserved for those convicted of violent offences, but now states can upload profiles of almost anyone charged with a crime. </li></ul></ul><ul><li>police are given the authority to collect DNA from any person arrested on suspicion of a &quot;recordable offence&quot;. These are people who may never have been charged, let alone convicted. </li></ul><ul><li>The best argument for including innocent people's profiles on the database is, of course, that it gets results </li></ul><ul><li>If your DNA is on the database it means that you are forever an automatic suspect for any crime in the future. It undermines the principle of presumptive innocence. </li></ul><ul><li>Being listed could jeopardize employment or foreign travel, and the information could be used for research on topics such as the genetic correlates of ethnicity or criminal behavior </li></ul>
  37. 39. <ul><li>How Do You Feel About DNA Data Bases, And Using Familial DNA? </li></ul><ul><li>Is It A Violation Of Privacy? </li></ul>
  38. 40. Exonerating The Wrongly convicted <ul><li>In February 1987, in Houston, Texas, a fourteen-year-old girl was forced into a car by two Latino men. She was taken to a house where both men raped her. After the sexual assault, she was placed in the car again and left on a roadside. </li></ul><ul><li>A man who served 17 years in prison for a rape he did not commit was formally declared innocent after DNA tests ruled out his guilt </li></ul><ul><li>George Rodriguez was cleared of all wrongdoing </li></ul><ul><li>Prosecutors say DNA tests rule out his participation in the 1987 rape </li></ul>A hair found in the victim’s underwear was said to be microscopically similar to the hair standard from George Rodriguez