Standard for On-Scene Collection and Preservation of Physical Evidence

1 OSAC 2021-N-0018

2 Standard for On-Scene

3 Collection and

4 Preservation of Physical

5 Evidence

6 Crime Scene Investigation & Reconstruction Subcommittee

7 Scene Examination Scientific Area Committee

8 Organization of Scientific Area Committees (OSAC) for Forensic Science

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Standard for On-Scene Collection and Preservation of Physical Evidence

9 Draft OSAC Proposed Standard

10 OSAC 2021-N-0018

11 Standard for On-Scene Collection and

12 Preservation of Physical Evidence

13 Prepared by 

14 Crime Scene Investigation & Reconstruction Subcommittee 

15 Version: 1.0 

16 March 2021 

17 Disclaimer:

18 This OSAC Proposed Standard was written by the Crime Scene Investigation & Reconstruction 

19 Subcommittee of the Organization of Scientific Area Committees (OSAC) for Forensic Science 

20 following a process that includes an open comment period . This Proposed Standard will be 

21 submitted to a standards developing organization and is subject to change. 

22 There may be references in an OSAC Proposed Standard to other publications under 

23 development by OSAC. The information in the Proposed Standard, and underlying concepts and 

24 methodologies, may be used by the forensic-science community before the completion of such 

25 companion publications. 

26 Any identification of commercial equipment, instruments, or materials in the Proposed Standard 

27 is not a recommendation or endorsement by the U.S. Government and does not imply that the 

28 equipment, instruments, or materials are necessarily the best available for the purpose. 

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Standard for On-Scene Collection and Preservation of Physical Evidence

29 Foreword 

30 This document provides standards for the on-scene collection and preservation of physical

31 evidence. Proper collection and preservation of physical evidence ensures that the integrity of the

32 evidence is maintained from the point of collection, through possible forensic examination, and to

33 the presentation of the evidence in the courtroom.

34 This document should be utilized in conjunction with local regulations and any requirements set

35 forth by entities examining collected evidence to inform or augment policies relating to the

36 collection and preservation of physical evidence.

37 This document has been drafted by the Crime Scene Investigation & Reconstruction Subcommittee

38 of the Organization of Scientific Area Committees (OSAC) for Forensic Science through a consensus

39 process.

40 This standard provides guidance on some safety issues but is not exhaustive. It is the responsibility

41 of the appropriate agency to develop a full health and safety plan.

42 Keywords : crime scene investigation, collection, preservation, physical evidence 

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43 Table of Contents

44 1 Scope 5

45 2 Normative References 5

46 3 Terms and Definitions 5

47 4 Collection and Preservation of Physical Evidence 6

48 4.1 Personal Protective Equipment 6

49 4.2 Chain of Custody 7

50 4.3 Evidence Packaging 7

51 5 Evidence Type Considerations 8

52 5.1 Biological evidence 8

53 5.2 Wet items 9

54 5.3 Greasy or oily items 9

55 5.4 Trace evidence 9

56 5.5 Fragile items 9

57 5.6 Friction ridge and other impressions 9

58 5.7 Gasses and liquids 10

59 5.8 Electronic Devices 10

60 6 Evidence Security 10

61 6.1 Sealing of evidence 10

62 6.2 Evidence Labelling 10

63 6.3 Evidence storage 10

64 Appendix A 12

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Standard for On-Scene Collection and Preservation of Physical Evidence

65 Standard for On-Scene Collection and Preservation of Physical Evidence

66 1 Scope 

67 This document provides standards and recommendations for the collection and preservation of

68 physical evidence during scene investigations. This document covers evidence handling

69 considerations intended to maintain the integrity of physical evidence so that reliable, accurate, and

70 relevant conclusions can be obtained in the course of an investigation. This document does not

71 pertain to the preservation methods needed during the initial survey and processing of the scene.

72 This document does not go into specific considerations for individual classes of evidence.

73 2 Normative References 

74 The following referenced document is indispensable for the application of this document. For dated

75 references, only the edition cited applies. For undated references, the latest edition of the

76 referenced document (including any amendments) applies.

77 Organization of Scientific Area Committees (OSAC) for Forensic Science, Scene Investigation

78 Subcommittee. Guiding Principles for Scene Investigation and Reconstruction [OSAC Proposed

79 Standard], March 2020.

80 ANSI-ASB Best Practice Recommendation 068: “Safe Handling of Firearms and 

81 Ammunition”, 1st Edition, 2020. 

82 3 Terms and Definitions 

83 For purposes of this document, the following definitions apply.

84 3.1

85 chain of custody

86 Chronological record of the handling and storage of an item from its point of collection to its final

87 return or disposal.

88 3.2

89 contamination

90 The undesirable introduction of a substance to an item at any point in the forensic

91 process. (ISO/FDIS 21043-1:2018[E])

92 NOTE This includes undesirable transfer of a substance within an item or between items, also referred to as

93 cross-contamination.

94 3.1

95 crime scene investigation

96 CSI

97 A scene investigation that involves an apparent criminal act.

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98 3.2

99 crime scene investigator

100 CSI

101 An individual, however named, who is responsible for performing elements of a scene investigation

102 that involves a potential criminal act.

103 3.5

104 law enforcement officer

105 LEO

106 Any public employee whose duties primarily involve enforcement or investigation of laws.

107 3.6

108 personal protection equipment

109 PPE

110 Equipment worn to minimize exposure to a variety of hazards such as body-fluids, irritants, or

111 contaminants. Examples of PPE: gloves, foot and eye protection, respirators, and full body suits.

112 3.7

113 physical evidence

114 Anything that can be physically collected, lifted, or imaged to inform the understanding of an

115 incident.

116 NOTE physical evidence may include biological evidence swabbings, impression, and print evidence in the

117 form of lifts, digital devices, and transitory evidence.

118 3.7

119 scene

120 A place or object that is subject to and/or requires forensic examination. (ISO/FDIS 21043-1:2018[E])

121 NOTE A crime scene is a common description of a scene where a presumed crime has been committed. The

122 scene can be a person or an animal.

123 3.6

124 scene investigation

125 An examination of a scene to locate, document, collect, and preserve items of potential evidentiary

126 value. (Guiding Principles)

127 NOTE Though commonly applied to criminal investigations, the same principles and methods can be more

128 broadly applied to scene investigations that are not criminal in nature.

129 3.7

130 scene investigator

131 An individual, however named, who is responsible for performing elements of scene investigation.

132 (Guiding Principles)

133 4 Collection and Preservation of Physical Evidence 

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134 Scene investigators shall communicate and cooperate with investigative personnel to ensure that

135 the scene examination is thorough and all evidence discovered is properly collected and/or

136 documented. The method employed for the collection and preservation of a particular item may

137 vary based on scene context and future analysis.

138 Evidence shall be collected and preserved in a manner that maintains evidence integrity by

139 preventing contamination, tampering, alteration, or loss of evidence. Evidence shall be retained in a 

140 manner that preserves the items’ integrity for analysis and introduction into a legal proceeding.

141 Throughout the process of collection, transportation and storage effort shall be taken to mitigate

142 unnecessary handling of items.

143 If the collection or preservation of a particular item is beyond the technical skills, knowledge, or

144 resources available to the crime scene investigator, specialized personnel within the department or

145 from an outside entity shall be contacted for consultation or assistance.

146 4.1 Personal Protective Equipment

147 4.1.1 Personal protective equipment (PPE) shall be utilized for both the safety of the wearer and

148 to protect the integrity of the evidence. PPE may consist of but is not limited to, gloves,

149 protective clothing, masks, eye protection, and respiratory equipment.

150 4.1.2 Scenes can be the source of various hazards including biological, chemical, physical, and

151 environmental hazards. Once the hazards present at the scene have been determined,

152 appropriate PPE shall be utilized by those processing the scene to protect from such

153 hazards. The scene should be continuously reevaluated to determine if alterations to the

154 level of PPE are needed for adequate personal protection.

155 4.1.3 PPE shall also be utilized as a means of contamination prevention. To prevent

156 contamination, PPE shall be single-use disposable or reusable and capable of being properly

157 sterilized from one scene to the next. Unused disposable gloves shall be worn when

158 handling items of physical evidence and shall be changed frequently. When handling

159 multiple items at a scene, PPE can be a source of cross contamination. PPE shall be changed

160 regularly to prevent cross contamination.

161 4.1.4 Care should be taken to avoid breathing, talking, or sweating directly over or otherwise

162 contaminating an item subject to DNA analysis. A mask and unused gloves should be worn

163 when working closely with evidence that may be subject to DNA analysis.

164 4.2 Chain of Custody

165 4.2.1 Chain of custody is the chronological and careful documentation to ensure traceability and

166 continuity of physical evidence in order to account for the integrity and possession of the

167 material. Chain of custody shall be established at the point of collection and maintained

168 through final disposition.

169 4.2.2 The chain of custody shall be documented for all items that are collected as evidence. This

170 documentation shall include the dates and times of any transfer to include the name of the

171 person or location to which the evidence is transferred. Each transfer shall be documented

172 by both parties.

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173 4.2.3 Transfer of evidence shall be purposeful and necessary. Evidence shall be transferred only to

174 persons that have a direct role in processing, storing, or investigating the items of evidence.

175 All evidence transfers shall be documented.

176 4.3 Evidence Packaging

177 4.3.1 Proper packaging is critical to preserving material physically as well as to preserving its

178 evidentiary value. Packaging protects against breakage, damage, contamination, prevents

179 chemical changes and deterioration, helps maintain chain of custody and provides for safe

180 handling, storage and shipment of hazardous material.

181 4.3.2 Each item of evidence shall be protected from loss, contamination, alteration, or tampering

182 prior to removing the item from the scene. If an item is too large to be placed in available

183 packaging, areas of evidentiary value shall be protected. There may be multiple acceptable

184 packaging options for different evidence types.

185 4.3.3 Attempts should be made to utilize final packaging in the field but conditions may exist

186 where temporary packaging needs to be used for transport. In this case, items shall be

187 repackaged to prevent degradation or tampering. For example, wet items may need to be

188 transported in plastic and dried prior to final packaging for long-term storage. Final,

189 long-term packaging shall minimize degradation to the item and preserve the evidentiary

190 value of the item to the extent possible.

191 4.3.4 Packaging and containers used to preserve evidence should be reasonably sized in relation

192 to the item. Excessively large or tight packaging should be avoided.

193 4.3.5 Packaging materials used for preservation of evidence shall be sturdy enough to avoid

194 damage to the packaging, damage to items within, or endangering personnel. Fragile and

195 sharp evidence may need additional clean protective padding.

196 4.3.6 Packaging shall be either single-use disposable or reusable and capable of being properly

197 sterilized prior to use. Note: Some sample types and analytical methods require that only

198 new, unused packaging be utilized.

199 4.3.7 Any tools utilized to place an item into its collection container shall be clean. Tools shall

200 either be single-use or properly sterilized prior to use.

201 4.3.8 Individual items of evidence should be packaged and sealed separately to maintain their

202 integrity and prevent cross-contamination. For items found commingled (such as cigarettes

203 within an ashtray), items may be packaged together or separately depending on

204 investigative needs.

205 4.3.9 Items and/or packages shall be marked in a manner that ensures that each item can be

206 uniquely associated with its documentation. Packaging shall include warning labels of any

207 hazards that the items may possess.

208 4.3.10 If an item with potential evidence is repackaged, original packaging shall be retained.

209 5 Evidence Type Considerations 

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210 This section provides general type-specific considerations for some common classes of evidence.

211 This list does not cover all possible evidence types, nor does it address all possible considerations

212 for each evidence.

213 5.1 Biological evidence

214 5.1.1 The collection and storage of biological evidence shall be packaged in a manner that limits

215 the degradation or tampering of the biological material.

216 5.1.2 In general, biological stains that are able to be dried shall be dried and packaged in

217 breathable packaging (e.g., paper bag) or in non-breathable packaging with a moisture

218 control mechanism (e.g., plastic tube with desiccant pack).

219 5.1.3 Liquid biological samples shall be collected in a sterile leak-proof, hard-sided container and

220 should be refrigerated or frozen for long-term storage depending on the type of sample.

221 5.1.4 NOTE The Biological Evidence Handbook: Best Practices for Evidence Handlers (NIST 2013) is

222 available for further guidance on the collection and preservation of biological evidence.

223 5.2 Wet items

224 5.2.1 Any item which could be degraded by prolonged exposure to moisture such as whole or live

225 plant evidence, clothes, or organic material shall be dried and packaged in breathable

226 packaging or packaging with a moisture control mechanism to prevent the accumulation of

227 moisture, mold, or mildew.

228 5.2.2 Wet items shall be packaged in a manner that prevents leakage from the point of collection

229 to a controlled area where the item can be dried and repackaged for long-term storage.

230 5.3 Greasy or oily items

231 5.3.1 Greasy or oily items shall be packaged in a manner that prevents leakage such as plastic

232 bags.

233 5.4 Trace evidence

234 5.4.1 Trace evidence shall be packaged in a manner that prevents loss of evidence or

235 contamination. If paper packaging is used, a bindle-type fold (figure 1 contains one possible

236 example) or double bagging procedure shall be used to prevent loss of small evidence

237 through seams.

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238 Figure 1 - Fold a clean sheet of paper into thirds, like a business letter; then fold into thirds from the

239 ends, creating nine “squares”; unfold; lay trace material in center “square”; re-fold as before, facing

240 one end of last fold into opposite end; seal with tape. (Figure courtesy of NFSTC@FIU).

241 5.4.2 Items suspected to be at risk of loss or damage during packaging should be collected

242 separately from substrates prior to transport..

243 5.4.3 Powdery or crystalline material should be packaged in a manner that prevents small

244 particles from loss.

245 5.5 Fragile items

246 5.5.1 Easily lost, broken, or destroyed evidence types shall be packaged and handled in a manner

247 that reduces surface contact, friction against the item, and possible damage from impacts to

248 the container.

249 5.6 Friction ridge and other impressions

250 5.6.1 Friction ridge and other impressions on the surface of items may be displaced or destroyed

251 by rubbing against packaging. These item types should be collected separately from

252 substrates (if possible), or placed in packaging which protects against abrasive contact or

253 other possible damage prior to transport.

254 5.7 Gasses and liquids

255 5.7.1 Gasses and some liquid chemicals can escape from common packaging like plastic bags and

256 paper bags. Further, plastic containers may break down and contaminate chemical evidence.

257 These types of evidence shall be packaged in non-porous containers such as glass jars or

258 lined paint cans to prevent evaporation or contamination

259 5.8 Electronic Devices

260 5.8.1 Digital information contained in electronic evidence can be accidentally or purposely

261 destroyed if physical items are not properly handled, protected, and prepared for storage.

262 When collecting an electronic device for purposes of investigating its digital media, content

263 shall be protected from alterations resulting in loss or contamination to the extent possible.

264 6 Evidence Security 

265 6.1 Sealing of evidence

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266 6.1.1 Upon collection, evidence shall be sealed in a manner that maintains evidence integrity by

267 preventing contamination, tampering, alteration, or loss of evidence.

268 6.1.2 If an item is too large to be placed in available packaging, areas of evidentiary value shall be

269 protected from contamination, tampering, alteration, or loss of evidence.

270 6.1.3 Long-term packaging shall include tamper detection ability, such as signed evidence tape.

271 a) If the packaging does not yet include a tamper detection mechanism and items are not

272 in the physical presence of the person currently in the custody of the items, items shall

273 be placed in a secure, temporary storage location with restricted access.

274 6.2 Evidence Labelling

275 6.2.1 Packaging shall be appropriately labeled to uniquely identify content, the circumstances of

276 collection, and to reflect any hazards.

277 6.2.2 Packaging or associated documentation should include specialized storage considerations

278 (e.g., refrigerated or frozen storage requirements) specific to the contents and subsequent

279 laboratory testing.

280 6.3 Evidence storage

281 6.3.1 From the time of collection until final disposition, all items shall be maintained and stored in

282 a secure manner which is able to prevent and detect tampering, alteration, loss or

283 contamination.

284 6.3.2 Storage areas for both short and long-term storage of evidence shall be secured and have

285 restricted access, where all personnel with access to the area are trained in the proper

286 handling of evidence.

287 6.3.3 Evidence shall be stored in a manner in which its integrity is preserved and it can be

288 uniquely associated with its documentation.

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289 Appendix A

290 (informative)

291 Bibliography

292 This is not meant to be an all-inclusive list as the group recognizes other publications on this

293 subject may exist. At the time this document was drafted, these were some of the publications

294 available for reference. Additionally, any mention of a particular software tool or vendor as part of

295 this bibliography is purely incidental, and any inclusion does not imply endorsement by the authors

296 of this document.

297 1] ASTM International, E1732-18, Standard Terminology Relating to Forensic Science, 2018

298 2] ISO/IEC Directives, 21043-1:2018 Forensic sciences- Part 1: Terms and definitions, 2018

299 3] National Forensic Science Technology Center, Crime Scene Investigation A Guide for Law

300 Enforcement, September 2013.

301 4] National Institute of Standards and Technology, & National Institute of Justice. The Biological

302 Evidence Handbook: Best Practices for Evidence Handlers, April 2013

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