DOI: 10.3886/icpsr37977.v1
title: Decontamination of Crime Scene Equipment: Evaluating Current Methods and Determining Best Practices, United States, 2019-2020
title: Version 1

description: A 2016 needs assessment conducted by the National Institute of Standards and Technology's Organization of Scientific Area Committees for Forensic Science (NIST/OSAC) Crime Scene Investigation (CSI) Subcommittee identified the decontamination of crime scene equipment as a gap that must be addressed. Currently, there are no widely accepted standard operating procedures (SOP) and/or best practices for crime scene investigators to follow regarding equipment decontamination. Furthermore, to date, there has been no peer-reviewed published research to assess the effectiveness of the different decontamination methods that are currently employed by crime laboratories and law enforcement agencies involved in crime scene investigations. Ineffective decontamination of crime scene equipment has the potential to lead to cross-contamination between scenes as well as secondary transfer to evidence after contact with equipment. With increased sensitivity of current DNA analysis protocols, the ineffective decontamination of CSI equipment has implication for wrongful convictions due to potential secondary DNA transfer.
To address this gap, and in response to the NIST/OSAC needs assessment, RTI International (RTI) performed a comprehensive evaluation of several decontamination methods on commonly used CSI equipment to provide the community with evidence-based recommendations of effective decontamination protocols. RTI identified reusable CSI equipment that is most likely to be contaminated with biological material after use at a crime scene based on literature searches, crime laboratory SOP reviews, and discussions with crime scene practitioners. Seven types of crime scene-related equipment were used to determine the extent of the effectiveness of nine frequently used decontamination methods. The total amount of DNA remaining on the equipment after a controlled decontamination was quantified using Quantifiler Trio DNA Quantification Kit and processed for short tandem repeat markers (STRs) with GlobalFiler. Quantifiler Trio includes a degradation index (DI) that provides an estimation of the quality of DNA in potentially degraded samples.
description: This research aimed to provide the crime scene investigation and forensic DNA communities with the following: 1) an understanding of the possibility of introducing biological contaminants to crime scene equipment during scene processing and the threat of cross-contamination between scenes; 2) a determination of whether the threat of biological contamination varies between equipment; 3) an assessment of the effectiveness of current methods in reducing true contamination threats; and 4) recommendations for the formulation of best practices regarding biological decontamination methods.
description: RTI identified seven pieces of reusable equipment that are most likely to be contaminated with biological material after use at a crime scene based on literature searches, standard operating procedures (SOP) reviews, and discussions with practicing crime scene investigators. The items were selected because they are commonly used and have a higher chance for primary and secondary transfer to evidence to occur after being handled with contaminates, gloves, or set on a contaminated surface. Additionally, some equipment may be routinely stored in a shirt or pants pocket (such as a pen or folding knife) and not subject to decontamination prior to use at another scene. The selected equipment included:
Camera
Camera strap
Clipboard
Evidence marker (placard)
Flashlight
Forceps (metal)
Folding knife
These pieces of equipment were used to determine the effectiveness of nine commonly used decontamination methods within the field. The cleaning agents used in the nine decontamination methods included:
10 percent Bleach Solution (The Clorox Company)
5 percent Virkon S (DuPont)
70 percent Isopropyl Alcohol Wipes (Pharma-C)
CaviWipes 1 (Metrex)
Clorox Wipes (The Clorox Company)
Lysol Dual Action Wipes (Reckitt Benckiser LLC)
Oxivir Tb Wipes (Diversey, Inc.)
Sani-Hands Instant Hand Sanitizing Wipes (PDI, Inc.)
Spartan CDC
Two biological fluids, blood and saliva, were selected to assess the efficacy of the nine decontamination methods. Blood was selected as a medium because it is a fluid that is commonly encountered at crime scenes, and epithelial cells in saliva was selected because it mimics contamination from trace amounts of touch DNA. The human whole blood and saliva samples were purchased from commercial suppliers.
description: Samples were prepared and collected in sets for each decontamination method and equipment item, which had been exposed to both sources of DNA. A total of 567 samples were prepared, collected, processed, and analyzed - 378 experimental samples, 126 positive controls (samples untreated with a decontamination method), and 63 negative controls.
description: Datasets: 
DS1: Decontamination of Crime Scene Equipment: Evaluating Current Methods and Determining Best Practices, United States, 2019-2020
description: Commonly used crime scene investigation equipment and cleaning agents used in decontamination methods.
description: These data are a Fast Track Release and are distributed as they were received from the data producer. All data files have been zipped for release, but not checked or processed. Please refer to the accompanying User's Guide for additional information, as well as the ICPSR README file for a brief description of the data available with this collection. Users should consult with the investigator(s) if further information is needed.The data package includes a zipped subfolder containing 207 .hid files. The .hid files are the study's raw data and need to be viewed in appropriate software (e.g., GeneMapper, GeneMarker).