Prompt Cast
The Challenges of DNA Evidence and the Science of Smell in Forensic Investigations
TLDR This episode of Science Versus delves into the complexities of DNA evidence in criminal investigations, highlighting the challenges of analyzing trace DNA and interpreting DNA mixtures. It also explores the emerging science of using trained dogs to detect the smell of human remains, discussing the current limitations and ongoing research in this field.
Timestamped Summary
00:00
This episode of Science Versus explores emerging forensic science, including the problems with DNA evidence in the Amanda Knox trial and the cutting-edge science of the smell of death in the Casey Anthony trial.
05:02
Scientists are becoming better at analyzing trace DNA, which is the small amount of DNA found in cells shed from sweat, coughing, or touching surfaces, and can be used as evidence in criminal investigations.
10:07
DNA analysis is reliable when there is a lot of DNA to work with, but becomes more complicated and prone to errors when there are only a few cells or the DNA is degraded.
14:43
DNA mixtures, which occur when there is more than one person's DNA in a sample, are difficult to interpret and can lead to unreliable results, but computer programs like StarMix are being used to untangle these mixtures with greater accuracy.
19:37
Computer programs like StarMix are being used to interpret DNA mixtures, but there are very few independent studies on their accuracy and reliability, and more work needs to be done, especially in cases with more than three people's DNA in the mix.
24:04
The Casey Anthony trial involved the alleged scent of a decomposing body in the trunk of her car, detected by a trained dog, which was used as evidence that her daughter's body had once been there.
28:46
Dogs, like Canine Garrus in the Casey Anthony trial, have been trained to smell dead bodies and can be trained to specifically search for the scent of human remains.
33:31
Dogs have been shown to be able to pick out the smell of human remains in contaminated carpet and soil, but without physical evidence, it is difficult to confirm their accuracy.
38:18
The research on the smell of death is still unfolding and there is no consensus on which chemicals are specific to human decomposition events.
42:53
Using chemical analysis to detect the presence of a dead body is still in the early stages of research and there is currently no reliable suite of chemicals that can be measured from decomposing human bodies.
