Spring 1998 Abstracts

AUTHORS: Chesterine Cwiklik of Cwiklik & Associates and Lynn D. McIntyre of Washington State Patrol Crime Laboratory

ABSTRACT: There is often more information in a shoeprint, tire track or other print than is obvious upon initial examination. A print that appears to exhibit only class characteristics may be rich in detail that is difficult to decipher. Using transparent overlays of exemplars to perform comparisons may not help much in elucidating subtle detail in the evidence print. We have been using a simple tracing method in working with difficult prints. The manual tracing method complements the use of transparent overlays of exemplars, and corrects for potential errors that may arise form the use of overlays alone. This method is especially useful for prints deposited in mud or blood, and prints on patterned surfaces. It has also proved useful in comparing evidence prints having design elements falling completely within the exemplar and that may otherwise be overwhelmed by it. Lastly, we have applied this in comparing stains.
The method involves manually tracing each individual mark in the area of the evidence print – even those marks that do not appear to be a part of the print – onto a piece of clear plastic. The tracing is then overlaid onto exemplars during comparison. Instead of “connecting the dots,” the examiner records the “dots” themselves, because this is the actual data. Several reference points should also be traces, perhaps in a different color. Usual reference points include a scale or recognizable objects in a photograph, the corners of a photograph or lift, a seam or edge of a fabric item, and so on.
In this talk, we will present several examples of manual tracings of prints and partial prints. We will also demonstrate the use of tracings in comparisons, and the records of the comparison by use of photocopies.

2.TITLE: "Interpreting a Group of Bloodstains Assisted by a Simple Overlay Tracing Method"

AUTHORS: Lynn D. McIntyre of Washington State Patrol Crime Laboratory and Chesterine Cwiklik of Cwiklik & Associates

ABSTRACT: This talk will illustrate the use of a simple tracing overlay method used to assist in interpreting a small group of bloodstains present on clothing evidence. The case in question involved a very bloody scene in which the victim was bludgeoned to death with a variety of objects. The identity of the assailant was not in question, rather his intent. The prosecution theory was that there was a protracted and brutal beating, which was intentional and pre-meditated, whereas the defense theory was that the victim initiated a homosexual encounter and that the murder was committed in the “heat of passion”. In trying to determine what really happened, we examined a number of items including the victim’s clothing.
An aggregate of bloodstains on the front hip area of the victim’s clothing, including a stain on the pains pocket and corresponding stains on the white shirt and undershorts were of particular interest. It was important to learn as much as we could about how they were deposited and by whom because of the question of sexual activity.
We considered several possibilities that might explain how the stains were deposited: 1.) someone at the medical examiner’s office had deposited the blood while handling the body, 2.) the defendant or victim had reached into the pants through the pocket, 3.) the defendant or the victim had reached beneath the pants, 4.) blood from the carpet had been transferred onto the clothing and 5.) the pants were open and then zipped and buttoned before the blows that produced the spatter occurred. We were able to rule out all but two hypotheses, that the pants were open at some point, or that someone had reached beneath the pants.
In this talk we will discuss the specific observations which allowed us to exclude some hypotheses and include some others. The overlay tracing method we used to assist in the interpretations will be described.

3. TITLE: "The Light Dawns"

AUTHOR: Dave Laycock of ISP - Forensic Services

ABSTRACT: A passenger vehicle collided with a 38,000 pound John Deere loader in broad daylight on a rural highway. The loader driver stated that the turn signals were on, signaling a left turn when the car hit the left rear wheel. The left signal lamps were submitted for examination; at first glance the left rear lamp appeared to exhibit cold fracture, but closer examination revealed a somewhat different story.

Arson

No Arson papers were presented at this meeting.

Wildlife Forensics

No Wildlife papers were presented at this meeting.

DNA and Conventional Serology

1. TITLE: "Validation of the Promega PowerPlex 16 STR Multiplex System on the ABI PRISM 310 Genetic Analyzer"

AUTHORS: Megan Ashton, Lori Hutchinson, Michelle Griffin, Stacey Brown of Montana Division of Forensic Science

ABSTRACT: The Promega PowerPlex 16 STR amplification system allows for simultaneous amplification of all 13 CODIS loci in addition to the amelogenin, Penta D and Penta E loci. Since only one amplification is necessary, this greatly expedites the processing of convicted offender and unsolved case samples to be submitted to CODIS.
In order to ensure the accuracy and precision of the system for convicted offender and casework samples, we performed an internal validation for the PowerPlex 16 system using the ABI PRISM 310 Genetic Analyzer. Several issues were addressed in the validation, including the detection of the minor profile in a mixture, sensitivity and stochastic effects in diluted samples, reproducibility of samples previously typed by the PowerPlex 1.1 system or the Profiler/Cofiler systems, heterozygote peak height rations, and stutter levels at each locus. We found the system to be highly sensitive, giving results at some loci using only 0.06ng of template DNA, with some complete profiles obtained at 0.25ng of template DNA. Our presentation will focus on these and other results obtained from the validation of this system.

Other

1. TITLE "National Law Enforcement and Corrections Technology Center (NLECTC)"

AUTHOR: Mike Epstein of NLECTC

ABSTRACT: The National Law Enforcement and Corrections Technology Center – Western Region (NLECTC-West) is part of a system of regional centers funded by the Department of Justice, National Institute of Justice to provide technical assistance to Public Safety Agencies at no cost. The NLECTC-West has provided Audio, Video, Computer and Metalurgical forensic services to agencies in Arizona, California, Hawaii, Idaho, Nevada, Oregon, Utah and Washington since 1995. Mike Epstein is the Manager of Forensic Services for the NLECTC-West. His presentation will include a description of the services available and some examples of past services provided.