Finding the way forward for forensic science in the US:a commentary on the PCAST report

A recent report by the US President’s Council of Advisors on Science and Technology (PCAST) [1] has made a number of recommendations for the future development of forensic science. Whereas we all agree that there is much need for change, we find that the PCAST report recommendations are founded on serious misunderstandings. We explain the traditional forensic paradigms of match and identification and the more recent foundation of the logical approach to evidence evaluation. This forms the groundwork for exposing many sources of confusion in the PCAST report. We explain how the notion of treating the scientist as a black box and the assignment of evidential weight through error rates is overly restrictive and misconceived. Our own view sees inferential logic, the development of calibrated knowledge and understanding of scientists as the core of the advance of the profession

Lab Retriever: a software tool for calculating likelihood ratios incorporating a probability of drop-out for forensic DNA profiles.

BackgroundTechnological advances have enabled the analysis of very small amounts of DNA in forensic cases. However, the DNA profiles from such evidence are frequently incomplete and can contain contributions from multiple individuals. The complexity of such samples confounds the assessment of the statistical weight of such evidence. One approach to account for this uncertainty is to use a likelihood ratio framework to compare the probability of the evidence profile under different scenarios. While researchers favor the likelihood ratio framework, few open-source software solutions with a graphical user interface implementing these calculations are available for practicing forensic scientists.ResultsTo address this need, we developed Lab Retriever, an open-source, freely available program that forensic scientists can use to calculate likelihood ratios for complex DNA profiles. Lab Retriever adds a graphical user interface, written primarily in JavaScript, on top of a C++ implementation of the previously published R code of Balding. We redesigned parts of the original Balding algorithm to improve computational speed. In addition to incorporating a probability of allelic drop-out and other critical parameters, Lab Retriever computes likelihood ratios for hypotheses that can include up to four unknown contributors to a mixed sample. These computations are completed nearly instantaneously on a modern PC or Mac computer.ConclusionsLab Retriever provides a practical software solution to forensic scientists who wish to assess the statistical weight of evidence for complex DNA profiles. Executable versions of the program are freely available for Mac OSX and Windows operating systems

The Probably and the Provable. By Jonathan L. Cohen

  Sight: Långholmen, Stockhomen ”Långholmensmarinstad” består av tre delar. En båtuppställningslada ett bostadsområde och en restaurang. Båtuppställningsladan har även en dubbel funktion som teater under sommar halvåret då Stockholmstads Parkteater får en fast spelplats och båtarna ligger i vattnet. Restarangen ligger i anslutning till båt huset och har en stor glas vägg som öppnar sig in mot Båtarna/teatern som skapar ett tydligt marint tema.   Bostadsområdet består av nio stycken radhus som vilar mot den befintliga Q-märkta fängelsemuren likt små japanskavillor med ljusgård. Det centralt placerade bostadshuset med sina fem våningar är lika högt som de gamla fängelsebyggnaderna. En lugn lummig innergård skapas emellan radhus och bostadshuset. Den lokala segel skolan får även husera i den nedre våningen av bostadshuset.      Sight: Långholmen, Stockhomen ”Långholmensmarinstad” consists of three parts. These are a large boathouse housing complex and a restaurant. The boathouse also has a double function as theatre space during the summer months when the Stockholm Parkteatern needs its seasonal venue. The restaurant is in direct adjacent to the Boathouse/theatre with a large glass wall which gives the restaurant a natural marina vibe. The housing complex consists of nine townhouses adjacent to the old heritage labelled prison wall, with small Japanese courtyards and one housing block. The housing block rises five story’s and has the same metric height as the surrounding historical prison buildings.   This creates a green peaceful inner courtyard in-between the townhouses and the housing block. The locale yachting club is given a natural haven in the ground floor space in the housing block

Explaining and trusting expert evidence: What is a ‘sufficiently reliable scientific basis’?

Through a series of judicial decisions and Practice Directions, the English courts have developed a rule that expert evidence must have ‘a sufficiently reliable scientific basis to be admitted’. There is a dearth of case-law as to what degree of reliability is ‘sufficient’. This article argues that the test should be interpreted as analogous to one developed in the law of hearsay: expert evidence (scientific or otherwise) must be ‘potentially safely reliable’ in the context of the evidence as a whole. The implications of this test will vary according to the relationship between the expert evidence and the other evidence in the case. The article identifies three main patterns into which this relationship falls. Whether the jury relies upon the evidence will depend upon what they regard as the best explanation of the evidence and how far they trust the expert. Whether their reliance is safe (as a basis for conviction) depends on whether they could rationally rule out explanations consistent with innocence, and whether the degree to which they take the expert’s evidence on trust is consistent with prosecution’s burden of proving the essential elements of its case, including the reliability of any scientific techniques on which it relies

The Critical Role of Statistics in Demostrating the Reliability of Expert Evidence

Federal Rule of Evidence 702, which covers testimony by expert witnesses, allows a witness to testify “in the form of an opinion or otherwise” if “the testimony is based on sufficient facts or data” and “is the product of reliable principles and methods” that have been “reliably applied.” The determination of “sufficient” (facts or data) and whether the “reliable principles and methods” relate to the scientific question at hand involve more discrimination than the current Rule 702 may suggest. Using examples from latent fingerprint matching and trace evidence (bullet lead and glass), I offer some criteria that scientists often consider in assessing the “trustworthiness” of evidence to enable courts to better distinguish between “trustworthy” and “questionable” evidence. The codification of such criteria may ultimately strengthen the current Rule 702 so courts can better distinguish between demonstrably scientific sufficiency and “opinion” based on inadequate (or inappurtenant) methods

Forensic Face Recognition: A Survey

Beside a few papers which focus on the forensic aspects of automatic face recognition, there is not much published about it in contrast to the literature on developing new techniques and methodologies for biometric face recognition. In this report, we review forensic facial identification which is the forensic experts‟ way of manual facial comparison. Then we review famous works in the domain of forensic face recognition. Some of these papers describe general trends in forensics [1], guidelines for manual forensic facial comparison and training of face examiners who will be required to verify the outcome of automatic forensic face recognition system [2]. Some proposes theoretical framework for application of face recognition technology in forensics [3] and automatic forensic facial comparison [4, 5]. Bayesian framework is discussed in detail and it is elaborated how it can be adapted to forensic face recognition. Several issues related with court admissibility and reliability of system are also discussed. \ud Until now, there is no operational system available which automatically compare image of a suspect with mugshot database and provide result usable in court. The fact that biometric face recognition can in most cases be used for forensic purpose is true but the issues related to integration of technology with legal system of court still remain to be solved. There is a great need for research which is multi-disciplinary in nature and which will integrate the face recognition technology with existing legal systems. In this report we present a review of the existing literature in this domain and discuss various aspects and requirements for forensic face recognition systems particularly focusing on Bayesian framework