Hello everyone and welcome to this session on understanding the issue with which forensic science can help. We are here in the laboratory that is dedicated to microscopy. It is in this lab that our students examined all sorts of material including fibers, paint, drugs, or glass. During this week, we will discuss cases where a small quantity of material was recovered. There is a general misconception that tackling the issue of a source of a trace is sufficiently informative in case. This week aims at showing that the reality is more subtle and is intrinsically linked to the concept of hierarchy of proposition and the necessity to assess the forensic findings within the framework of circumstances of the case as a whole. To demonstrate this point, cases based on DNA evidence and Gunshot Residue or in English, Firearms Discharge Residues, will be analyzed and discussed. Gunshot Residues, the acronym uses GSR, are the fine particles which are expelled from a firearm when a shot is made. These particles will land on the hands respective to the garment or the environment in which the shooting occurred. First, with the first case, we will demonstrate that the DNA observations providing information towards the source of the DNA may not be at the core of the issue in the case. More and more, the source of the DNA is not challenge anymore, but it is how the DNA got there that is in dispute. This week is organized in different videos, in part A, Alex and Tasha will discuss the Weller case which is a case involving the discovery of female DNA under the nails of Mr. Weller. Franco will present you the key concept of a hierarchy of propositions. In this case, you cannot handle the complexity of the issues without it. We will also have a short interview with my very good friends, Dr. Ian Evett and Professor Graham Jackson, who were both involved in the case assessment and interpretation initiative, to which I had also the privilege to take part with other colleagues. They will tell you more about CAI and in particular demonstrate why the hierarchy of proposition is a powerful tool to structure our thinking. In part B, Alex and Tasha will present the Barry George case which involved the shooting of a famous news presenter Jill Dando. We will also visit together the firearms section of our laboratory to teach you the basic concepts associated with gunshot residue. The case of Barry George, was referred to the Criminal Case Review Commission or CCRC. An organ in England and Wales, that has been set up following miscarriages of justice involving forensic science as, for example, in the case of the Birmingham Six. The CCRC can be called upon by any prisoner thinking that he's a victim of a miscarriage of justice. It is a unique institution that we would like to see in other countries. In part C, Franco and Tasha will discuss two other DNA cases. One case involved Mr. Butler, a taxi driver who was accused of murdering a woman. We will hear in that context, Dr. Sue Pope, a very experience forensic scientist who also was a past colleague of mine and very good friend. She walked on this case and was instrumental to warn against the risk of jumping to ask the conclusions. The last case, where Mr. Nealon and was accused is a sexual assault where no corresponding DNA was found. These case will allow us to consider the meaning to be attached to the absence of evidence. Needless to say that we will challenge the well-known adage saying, absence of evidence is not evidence of absence. Quite a busy weekends, and quite an exciting week in front of us. That leads me to introduce the objectives of this week which are as follows. The first is to understand this concept of hierarchy of proposition and being able to distinguish between the levels in that hierarchy. The second is to understand the difference between source level issues, and activity level issues. The third, to recognized when forensic scientists have to deal with a case at activity level versus source level. The fourth is to identify the factors and data the forensic scientist needs to consider properly when assigning the probability of the evidence given activity level propositions. So thank you for watching.
