Over fifty years ago, a young girl was walking from the nearby laundromat when she was abducted, sexually assaulted and strangled. Twenty years later, a woman’s body was found by the side of the road in St. Cloud, Florida. She had been stabbed over seventeen times. In the same year, a partial set of remains were recovered from a body of water. Although all three of these homicide cases had different circumstances, they all had one thing in common. They all became cold after traditional short tandem repeat (STR) testing failed to provide an investigative lead.
STR testing has long been considered the gold standard of forensic DNA testing. What happens though when there are no hits in the Combined DNA Index System (CODIS)? What do you do next? This is where using sequencing to obtain single nucleotide polymorphism (SNP) profiles can be helpful.
Choosing the best technology fit for the evidence when attempting to obtain a SNP profile suitable for upload to public databases that allow lab enforcement profiles relies on several factors. Not all SNP technologies are made equal and one may be more suitable than another depending on the case. The analyst should be triaging cases by asking several questions prior to sequencing. What is the quantity and quality of the DNA sample? Is the sample degraded? What is the level of bacterial contamination within the sample? Should you perform additional extractions to try and maximize the amount of DNA prior to sequencing? What other testing has already been done? Is there already an STR profile that is being searched in CODIS? Is the profile a mixture?
This presentation will discuss how cases are triaged and sent down one of three paths: targeted sequencing, array testing, or whole genome sequencing. In each of the three cases reviewed in this presentation, a different technology was used based on the answers to this question. After years of waiting, the victims’ families finally had some closure thanks to SNP testing.
Over fifty years ago, a young girl was walking from the nearby laundromat when she was abducted, sexually assaulted and strangled. Twenty years later, a woman’s body was found by the side of the road in St. Cloud, Florida. She had been stabbed over seventeen times. In the same year, a partial set of remains were recovered from a body of water. Although all three of these homicide cases had different circumstances, they all had one thing in common. They all became cold after traditional short tandem repeat (STR) testing failed to provide an investigative lead.
STR testing has long been considered the gold standard of forensic DNA testing. What happens though when there are no hits in the Combined DNA Index System (CODIS)? What do you do next? This is where using sequencing to obtain single nucleotide polymorphism (SNP) profiles can be helpful.
Choosing the best technology fit for the evidence when attempting to obtain a SNP profile suitable for upload to public databases that allow lab enforcement profiles relies on several factors. Not all SNP technologies are made equal and one may be more suitable than another depending on the case. The analyst should be triaging cases by asking several questions prior to sequencing. What is the quantity and quality of the DNA sample? Is the sample degraded? What is the level of bacterial contamination within the sample? Should you perform additional extractions to try and maximize the amount of DNA prior to sequencing? What other testing has already been done? Is there already an STR profile that is being searched in CODIS? Is the profile a mixture?
This presentation will discuss how cases are triaged and sent down one of three paths: targeted sequencing, array testing, or whole genome sequencing. In each of the three cases reviewed in this presentation, a different technology was used based on the answers to this question. After years of waiting, the victims’ families finally had some closure thanks to SNP testing.
Workshop currently at capacity. A waitlist is available to join on our registration page.
Chief Operating Officer and Technical Leader, DNA Labs International
Cristina Servidio is the Chief Operating Officer and Technical Leader at DNA Labs International, where she manages laboratory operations and oversees the analysis of forensic DNA evidence.
