The use of a 3-D laser scanner to document ephemeral evidence at crime scenes and postmortem examinations

Proper documentation of physical evidence at both crimes scenes and postmortem examination is crucial for downstream analysis, interpretation, and presentation in court. Ephemeral or transient evidence poses particular challenges to investigators, as its very nature renders it difficult or impossible to seize and maintain in its original physical state. The use of a hand-held three-dimensional (3-D) laser scanner is proposed to capture and document such evidence, both in the field and at autopsy. Advantages of the scanner over traditional means of documentation such as photography or casting include the ability to obtain measurements in all dimensions, the ability to reconstruct missing elements, and the ease with which generated images can be interpreted by the jury at trial. Potential scenarios warranting the use of the scanner are identified, and the limitations of its use are discussed.     

The value of DNA material recovered from crime scenes

Abstract:  DNA material is now collected routinely from crime scenes for a wide range of offenses and its timely processing is acknowledged as a key element to its success in solving crime. An analysis of the processing of approximately 1500 samples of DNA material recovered from the property crime offenses of residential burglary, commercial burglary, and theft of motor vehicle in Northamptonshire, U.K. during 2006 identified saliva and cigarette ends as the main sources of DNA recovered (approximately 63% of samples) with blood, cellular DNA, and chewing gum accounting for the remainder. The conversion of these DNA samples into DNA profiles and then into matches with offender profiles held on the U.K. National DNA database is considered in terms of the ease with which Crime Scene Examiners can recover DNA rich samples of different sources, the location of the DNA at the crime scene, and its mobility. A logistical regression of the DNA material recovered has revealed a number of predictors, other than timeliness, that greatly influence its conversion into a DNA profile. The most significant predictor was found to be Crime Scene Examiner accreditation with offense type and DNA sample condition also being relevant. A similar logistical regression of DNA samples profiled that produced a match with an offender on the U.K. National DNA database showed no significance with any of the predictors considered.     

物证鉴定中的物证污染问题

物证污染是影响物证鉴定结果的最重要因素之一,它会损害物证鉴定结论质量甚至造成错误的鉴定结论。随着以法医DNA检验为代表的物证鉴定技术检验灵敏度的提高,物证污染出现的可能性及其造成的危害程度都显著增加。物证污染有多种形式和来源,可能发生在犯罪现场或实验室。采取适当的污染防范措施可以有效降低物证污染发生的可能性,及时监测和发现物证污染可以将污染造成的危害降到最低。     

Latent evidence detection using a combination of near infrared and high dynamic range photography: an example using bloodstains

In this paper, we use bloodstains to illustrate an approach for identifying latent evidence on dark cloth using near infrared (NIR) photography combined with high dynamic range (HDR) photography techniques. NIR photography alone has been used to capture latent evidence that cannot be seen in normal ambient light. HDR techniques combine multiple bracketed photographs of the same image to increase the dynamic range of the photograph which can provide greater contrast. Using NIR photography alone, we were able to detect a bloodstain up to a 1/16 dilution, an improvement over previous studies. Combining NIR photography with the HDR process resulted in a noticeable increase in visibility up to 1/16 dilution when compared to NIR photographs alone. At 1/32 dilution, we were able to detect bloodstains that were not visible using NIR alone. NIR is a useful tool for imaging latent evidence, and combining NIR with HDR consistently provides better results over NIR alone.     

Internet mediated crimes and theoretical approaches

Purpose: in the literature, the term ‘Internet crime’ has been coined to indicate the scenario in which a victim of homicide or other crimes is met through a chat room, and lured to death at the hands of the murderer. Various criticisms have been made of this new concept, on the grounds that the outcome is no different from that of other crimes committed without the use of Web resources, and so the method used has no particular influence. Indeed, it has been claimed that informatic crime just reflects a technological change in the nature of crime rather than a new form of criminal behavior attributable to the use of the Internet for criminal purposes. Method: our reflections were prompted by our experience as expert forensic psychiatry witnesses in three cases in which the aggressors had confessed to having had an exclusively virtual relationship with the victims, in which they spent a lot of time daily in a chat room. Conclusion: this scenario offers points for reflection on the nature of Web-mediated victim–aggressor interactions, to assess the effects on the planning and commission of the crime. Discussion. it’s our opinion that there really is such a thing as Internet-correlated crime, because in this case the quality and quantity of the Internet interactions progressively altered the men’s perception of the real relationship between themself and their victims.     

Estimation of stature from hand impression: a nonconventional approach

Stature is used for constructing a biological profile that assists with the identification of an individual. So far, little attention has been paid to the fact that stature can be estimated from hand impressions left at scene of crime. The present study based on practical observations adopted a new methodology of measuring hand length from the depressed area between hypothenar and thenar region on the proximal surface of the palm. Stature and bilateral hand impressions were obtained from 503 men of central India. Seventeen dimensions of hand were measured on the impression. Linear regression equations derived showed hand length followed by palm length are best estimates of stature. Testing the practical utility of the suggested method on latent prints of 137 subjects, a statistically insignificant result was obtained when known and estimated stature derived from latent prints was compared. The suggested approach points to a strong possibility of its usage in crime scene investigation, albeit the fact that validation studies in real-life scenarios are performed.     

An investigation into the differentiating characteristics between car key burglars and regular burglars

Car key burglary has recently become the focus of empirical investigation as offenders, no longer able to steal vehicles without first obtaining their keys, resort to "burgling" target properties. Research surrounding the modus operandi of these offenses is beginning to emerge; however, little attention has been paid to investigating the characteristics of car key burglary offenders. Challenging the assumption that car key burglary offenses are perpetrated by regular burglars, this study aims to differentiate between offenders. Logistic regression analysis of 110 car key and 110 regular burglary offenders revealed that car key burglars are more likely to have previous vehicle theft convictions and are also more likely to be detected on information supplied to the police than regular burglars. Regular burglars are more likely to have previous shoplifting convictions. It was concluded that car key burglars are a distinct sample of offenders and the implications of these findings are discussed.