DNA technology in court Dan E. Krane, Wright State University, Dayton, OH Forensic DNA Profiling Video Series Forensic Bioinformatics (www.bioforensics.com)

DNA technology in court Criminal Prosecution Unprecedented sensitivity and specificity for typing biological samples Growing use of databanks and dragnets to identify suspects Rapidly becoming cheaper and faster

Possible DNA sources Slide illustrating that with STR’s we can do “non-conventional” evidence such as dandruff and skin cells from the handle of a knife.

DNA technology in court Criminal Defense Unprecedented sensitivity and specificity for typing biological samples Potential support for alternative theories of the case Generation of alternative suspects In a July, 2003 interview with investigators, Kobe Bryant stated that he had had consensual sex with a 19-year-old hotel employee. He is shown here with his attorney Pamela Mackey.

DNA technology in court Post-conviction exonerations (300 as of September, 2012) based on DNA evidence have revealed problems with the justice system Damon Thibodeaux had been on death row in Louisiana since October 1997 until he was exonerated of the murder and rape of his 14-year old step-cousin. He was the 300th to be exonerated by DNA evidence and the 18th to have served time on death row. The 300 DNA exonerees served a combined total of 4,013 years in prison for crimes that they did not commit. In almost half of the cases the true perpetrator was caught. But, had the true perpetrator been correctly captured in the first place more than 130 violent crimes could have been prevented. The Innocence Project only takes on cases if three criteria are met: 1) the convicted individual has maintained their innocence throughout, 2) DNA test results would be able to prove innocence, and 3) material is available for DNA testing.

Factors associated with wrongful convictions Saks & Koehler, Science (2005) The Coming Paradigm Shift in Forensic Identification Science, Science, 5 August, 2005, 309:892-895. Based on case analysis of 86 DNA exonerations. Red bars indicate factors related to forensic science. Percentages exceed 100% because more than one factor was found in many cases.

What is a good source of DNA? Blood, saliva, semen, tissues, pretty much anything that comes in contact with a person.

DNA content of biological samples Trillions of cells

DNA content of biological samples Trillions of cells Roughly 100 cells

DNA content of biological samples Trillions of cells Roughly 100 cells Each cell contains 6 to 7 pg of DNA DNA profiling kits generally recommend using between 500 and 1,000 pg of template DNA

DNA content of biological samples Trillions of cells Roughly 100 cells Each cell contains 6 to 7 pg of DNA DNA profiling kits generally recommend using between 500 and 1,000 pg of template DNA That works out to roughly 100 to 200 cells

What is a picogram? 1 gram = 1/4th of a packet of sugar 1 milligram = a single crystal of sugar 1 nanogram = one 1000th of a crystal of sugar 1 picogram = one billionth of a gram

What is a good source of DNA? Blood, saliva, semen, tissues, pretty much anything that comes in contact with a person. But, the presence of a DNA profile says nothing about the time frame or circumstances of its transfer.

How is DNA analyzed? Isolation and purification PCR amplification Size fractionation Computer processing Statistical weighting

DNA technology in court Used in prosecutions, defenses, and post-conviction

DNA technology in court Used in prosecutions, defenses, and post-conviction DNA tests are very sensitive

DNA technology in court Used in prosecutions, defenses, and post-conviction DNA tests are very sensitive Test results need to be interpreted carefully

DNA technology in court Dan E. Krane, Wright State University, Dayton, OH Forensic DNA Profiling Video Series Forensic Bioinformatics (www.bioforensics.com)