title: Persistence of touch DNA on burglary-related tools.
abstract: Experts are increasingly concerned by issues regarding the activity level of DNA stains. A case from our burglary-related casework pointed out the need for experiments regarding the persistence of DNA when more than one person touched a tool handle. We performed short tandem repeat (STR) analyses for three groups of tools: (1) personal and mock owned tools; (2) tools, which were first "owned" by a first user and then handled in a burglary action by a second user; and (3) tools, which were first owned by a first user and then handled in a moderate action. At least three types of tool handles were included in each of the groups. Every second user handled the tool with and without gloves. In total, 234 samples were analyzed regarding profile completeness of first and second user as well as properties like detectable major profile or mixture attributes. When second users simulated a burglary by using a tool bare handed, we could not detect the first user as major component on their handles but attribute him to the stain in 1/40 cases. When second users broke up the burglary setup using gloves, the first user matched the DNA handle profile in 37% of the cases. Moderate use of mock borrowed tools demonstrated a material-dependent persistence. In total, we observed that the outcome depends mainly on the nature of contact, the handle material, and the user-specific characteristics. This study intends to supplement present knowledge about persistence of touch DNA with a special emphasis on burglary-related cases with two consecutive users and to act as experimental data for an evaluation of the relevance of alleged hypotheses, when such is needed in a court hearing.
authors.affiliation: Institute of Legal Medicine, Albert-Einstein-Allee 23, 89081, Ulm, Germany. celine.pfeifer@uniklinik-ulm.de.
authors.forename: Céline M
authors.initials: CM
authors.lastname: Pfeifer
authors.affiliation: Institute of Legal Medicine, Albert-Einstein-Allee 23, 89081, Ulm, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Wiegand
mesh_terms: D004247:DNA / Q000302:isolation & purification*; D016172:DNA Fingerprinting; D005260:Female; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D008855:Microscopy, Electron, Scanning; D060888:Real-Time Polymerase Chain Reaction; D012867:Skin / Q000648:ultrastructure; D013800:Theft; D014110:Touch
chemical_list: D004247:DNA
keywords: Burglary; DNA transfer; Forensic science; Gloves; Persistence; Touch DNA