An Introduction to Building 3D Crime Scene Models Using SketchUp
Elissa St. Clair, Andy Maloney, and Albert Schade III
Abstract: Crime scene investigators generally have two options when they need to create a three-dimensional (3D) model of a crime scene: enlist the services of an expert 3D modeller who specializes in graphic modelling or learn one of the full-fledged modelling tools to create the model themselves. Many modelling tools have a very steep learning curve, so the time required to invest in learning a tool to get even a simple result is often prohibitive. In this article, we introduce SketchUp (version 8) as a relatively easy-to-use tool for modelling crime scenes in 3D, give an example of how the software can be applied, and provide resources for further information.
Supplemental Materials: The supplemental materials may be downloaded here and consist of the following:
- the complete SketchUp model for the crime scene example used in this article
- the SketchUp file for the muryoung body model posed for the example crime scene in this article
- the SketchUp file for the new male body model, mentioned in the Resources section, posed for the example crime scene in this article
Aspects Influencing the Entomological Postmortem Interval in Crime Scene Reconstruction
Tom Adair, MS
Abstract: The pathological postmortem interval (PMI), or time since death estimate, is widely understood among crime scene reconstructionists, pathologists, and prosecutors. Unlike the pathological PMI, the entomological PMI is not strictly an estimate of the time since death. This paper will discuss the entomological PMI and the environmental and cultural factors that may influence it.
Identification of a Second Suspect via Stomach Contents at Autopsy
Abstract: A case report describing the examination of stomach contents at the autopsy of a robber, who was shot and killed during the commission of his crime, which led to the identification of the second and outstanding robber. During autopsy, digested stomach contents gave the attending forensic analyst information regarding a possible location of two robbery suspects prior to committing their crime. This information led the analyst to a Wendy’s fast food restaurant near the vicinity of the crime and video analysis from the restaurant’s surveillance system provided investigators with the face of a known criminal they could identify.
Edward M. Robinson and Julie Flanagan
Abstract: Rhino Photogrammetry is introduced, to minimize or eliminate the need for measurements at medium to small crime scenes, here it is critical to get in and out of the area as quickly as possible. The main benefit is the huge time savings based on eliminating the need to have every item of evidence measured twice by either baseline coordination or triangulation. Photogrammetry, or the technique for extrapolating accurate measurements from photographs, can be used to derive the same measurements as accurately as if measured with traditional tape measures. Using Rhino Photogrammetry would be optimal when bad weather is approaching and will destroy the evidence if left outdoors during storms or when the military needs to recover as much evidence as possible before becoming targets of enemy forces.
PDF: Rhino Photogrammetry
The Survival of Neat and Cleaned Blood after the Application of Wallpaper
Ivanie Stene and Tom Adair, MS
Abstract: We report on a study in which neat (undiluted) and cleaned bloodstains were covered with commercial wallpaper in order to test methods of discovery and recovery of said stains. Cleaned and camouflaged (covered) bloodstains pose significant challenges to the crime scene reconstructionist. Criminals may employ a variety of methods to destroy bloodstain evidence from a simple cleaning with water to extreme measures such as covering the cleaned areas with paint or wallpaper. This study supports the conclusion that neat and cleaned bloodstains are very difficult to detect through wallpaper but may be detected once the wallpaper is removed.
Touch DNA: Forensic Collection and Application to Investigations
Angela L. Williamson
Abstract: Touch DNA refers to the DNA that is left behind from skin cells when a person touches or comes into contact with an item. However, since Touch DNA (also referred to as wearer or contact DNA) is invisible to the naked eye, and is usually deposited in smaller amounts than the DNA found in bloodstains or other body fluids, it is more difficult to identify areas where skin cells may be present. As such, it can be quite challenging to obtain DNA profiles from these samples. Obtaining successful Touch DNA results depends on recognizing items which may be suitable for Touch DNA analysis, proper collection/storage of these items, and the subsequent use of the optimal sampling technique that will recover the highest number of skin cells.