CASE REPORT Blood-Spatter Patterns Hands Hold Clues for the Forensic Reconstruction of the Sequence of Events Kathrin Yen, MD, Michael J. Thali, MD, Beat P. Kneubuehl, Dr. Sc. Forens., Oliver Peschel, MD, Ulrich Zollinger, MD, and Richard Dirnhofer, MD Abstract: Biologic and nonbiologic traces on the hands are of particular importance for the forensic reconstruction of shooting incidents; gunpowder residue analysis in particular helps determine whether the gunshot is close range or distant. In crime scene investigation, knowledge about the morphology of bloodstain pat- terns–including gunshot-related back spatter– has increased since various experimental examinations have been performed in the last years; nowadays, these traces are frequently used for forensic crime scene reconstruction. The goal of this study was to deduce the position and orientation of the hands, and therefore the firearm, according to the bloodstain patterns on the hands of the deceased. For this purpose blood-spatter stains on the hands were examined on site in 5 suicides caused by gunshot. In all cases, forensically relevant conclusions regarding forensic reconstruction were enabled through close exam- ination of the spatter marks. Therefore, in shooting incidents, anal- ysis and documentation of blood-spatter findings on the hands is recommended before hands are tested for gunpowder residue or wrapped for the transport of the body. Key Words: gunshot wounds, bloodstain pattern analysis, back spatter, reconstruction (Am J Forensic Med Pathol 2003;24: 132–140) I n shooting incidents, the first point to be addressed during forensic investigation is whether it is an instance of murder, accident, or suicide. 1 This is where close examination of the hands can yield valuable clues. Gunpowder residue, but also lesions to the hands caused by the firearm (trigger, breech, etc.), is of importance as well as biologic material such as blood, fatty tissue, or brain tissue spattered onto the trigger hand or the supporting hand. 2–6 Concerning blood spatter on the hands, the literature and textbooks usually draw attention merely to the existence of these stains; in contrast to that in the crime scene investi- gation, the shape of individual droplets, as well as the larger pattern and alignment of spatter marks, is a subject only in rare cases. 7,8 Even specialists in bloodstain interpretation 9,10 limit themselves to a rough description of possible droplet arrangements on the hands. This dearth of exact information is partially alleviated by evidence collected in several publications 7,11,12 , which indicates that spatter marks (on the trigger hand) are primarily located on the back of the first 3 digits and on the back of the hand. The spattered character of bloodstains was also alluded to by E. v. Hofmann 13 in 1898. He explained it as the result of retrograde expulsion of blood and tissue from the entry wound onto the trigger hand. This explanation anticipated the first observations that proved that blood from the entry wound spreads in a retrograde, conical shape toward the trigger hand and supporting hand. 6,9,14 Zwingli 7 concurred, observing that the droplets fanned out radially with increasing distance from the entry wound. This phenomenon was confirmed by the experiments conducted by Karger ( 11,15,16 and references therein) and the observations by Bevel and Gardner. 9 In the investigation of bloodstain patterns on the hands, the particular set of marks termed impact spatter 9,10,12 is of major importance to the forensic examiner. Forward spatter or back-spatter impact stains occur when blood receives some impact and is divided into smaller droplets; back-spatter patterns in shooting incidents are the result of blood droplets expelled from the entry wound hitting the foremost parts of the trigger hand, weapon, and supporting hand. According to the literature, they qualify as “medium to high velocity spatter.” 10 Rounded spatter marks occur when the droplets hit the surface at Manuscript received November 1, 2002; accepted November 14, 2002. From the Institute of Forensic Medicine, University of Bern, Switzerland (K.Y., M.J.T., U.Z., R.D.); Weapon and Ammunition Test Center, Defense Procurement Agency, Thun, Switzerland (B.P.K.); and the Department of Legal Medicine, University of Munich, Germany (O.P.). Address correspondence and reprint requests to Kathrin Yen, M.D., Institute of Forensic Medicine, University of Bern, IRM Buehlstrasse 20, CH 3012 Bern, Switzerland; E-mail: yen@irm.unibe.ch Copyright © 2003 by Lippincott Williams & Wilkins 0195-7910/03/2402-0132 DOI: 10.1097/01.paf.0000065164.92878.2f The American Journal of Forensic Medicine and Pathology • Volume 24, Number 2, June 2003 132