Standard for Initial Response at Scenes by Law Enforcement

1 OSAC 2021-N-0016

2 Standard for Initial

3 Response at Scenes by Law

4 Enforcement

5 Crime Scene Investigation & Reconstruction Subcommittee

6 Scene Examination Scientific Area Committee

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

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Standard for Initial Response at Scenes by Law Enforcement

8 Draft OSAC Proposed Standard

9 OSAC 2021-N-0016

10 Standard for Initial Response at Scenes

11 by Law Enforcement

12 Prepared by 

13 Crime Scene Investigation & Reconstruction Subcommittee 

14 Version: 1.0 

15 March 2021 

16 Disclaimer:

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

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

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

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

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

22 by OSAC. The information in the Proposed Standard, and underlying concepts and methodologies, 

23 may be used by the forensic-science community before the completion of such companion 

24 publications. 

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

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

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

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28 Foreword 

29 This standard specifies best practices to be employed by law enforcement officers (LEO) 

30 when they arrive at an incident which could be expected to become the subject of criminal or 

31 civil litigation. This standard applies to instances where the responding person’s primary 

32 responsibility is initial response and securing the scene and not scene examination and 

33 evidence collection. In instances where the responding LEO is also responsible for scene 

34 examination, documentation, and evidence recovery, they should refer to applicable 

35 additional standards. This document recommends generally accepted professional principles 

36 and practices. The details and issues of each situation and scene require consideration and 

37 will dictate the course of actions to be undertaken by the LEO. Deviations from this standard 

38 should be based on specific articulable circumstances. This standard cannot replace 

39 knowledge, skill, or ability acquired through appropriate education, training, and experience 

40 and should be used in conjunction with sound professional judgement. This standard 

41 provides guidance on some safety issues but is not exhaustive. It is the responsibility of the 

42 appropriate agency to develop a full health and safety plan. 

43 This standard is not intended to make agency-specific protocols. This document is intended 

44 to inform individual agency protocols dictating how LEOs are to respond to, approach, and 

45 enter a scene with a focus on evidence integrity and consideration for safety, security, and 

46 medical intervention. This document is intended to provide investigators with a safer work 

47 environment and to limit alterations to a scene, witnesses, persons of interest, and evidence 

48 so that all aspects of the scene are in a substantially similar condition as they were found 

49 when law enforcement initially encountered them. 

50 Keywords: Crime scene, document, examination, law enforcement, response, investigation

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51 Table of Contents

52 1 Scope..................................................................................................................7

53 2 Normative References............................................................................................7

54 3 Terms and Definitions............................................................................................7

55 4 Requirements.......................................................................................................8

56 4.1

57 Overview........................................................................................................................8

58 4.2 Arrival Procedure......................................................................................................8

59 4.3 Safety

60 Considerations..................................................................................................................8

61 4.4 Medical Intervention..............................................................................................9

62 4.5 Assessing the Scene....................................................................................................9

63 4.6 Scene Containment and Control.......................................................................................9

64 4.7 Evidence Preservation..............................................................................................10

65 4.8 Turning a Scene Over to Investigators............................................................................10

66 4.9 Recording Scene Conditions........................................................................................10

67 Annex A (informative)

68 Bibliography...............................................................................................................11

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69 Standard for Initial Response at Scenes by Law Enforcement 

70 1 Scope 

71 This standard describes the protocols required for the initial response by law enforcement to scenes.

72 These protocols include: arrival procedure, safety considerations, medical intervention, assessing the

73 scene, scene containment and control, evidence preservation, turning the scene over to investigators,

74 and document actions and observations. It does not include protocols for a complete scene

75 investigation.

76 2 Normative References 

77 Guiding Principles for Scene Investigation and Reconstruction [OSAC Proposed Standard]

78 3 Terms and Definitions 

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

80 3.1

81 crime scene investigation

82 CSI

83 A scene investigation that involves a potential criminal act.

84 3.2

85 crime scene investigator

86 CSI

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

88 involves a potential criminal act.

89 3.3

90 crime scene preservation

91 See scene preservation.

92 3.4

93 contamination

94 The undesirable introduction of a substance to an item at any point in the forensic process. Note: This

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

96 cross-contamination. (ISO 21043-1)

97 3.5

98 law enforcement officer (LEO)

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

100 3.6

101 personal protection equipment (PPE)

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

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

104 3.8

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105 scene

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

107 NOTE: A crime scene is a common description of a scene where a presumed crime has been

108 committed. The scene can be a person or an animal.

109 3.9

110 scene investigation

111 An examination of a scene to locate, document, collect, and preserve items of potential evidentiary value.

112 [Guiding Principles]

113 3.10

114 scene investigator

115 An individual, however named, who is responsible for performing elements of scene investigation. [Guiding

116 Principles]

117 3.11

118 scene preservation

119 The intentional act of refraining from any activity that may alter a scene or anything contained within

120 the scene. [Guiding Principles]

121 4 Requirements 

122 4.1 Overview

123 4.1.1 Every scene has the potential to yield evidence that may aid in a criminal

124 investigation. As such, the first responding LEO to a scene shall take all reasonable actions to

125 preserve the scene in order to maintain evidence integrity until a designated scene

126 investigator (CSI) is able to respond.

127 4.1.2 Scene investigation is the responsibility of the responding officer in some jurisdictions

128 while in others a dedicated unit is deployed to a scene and the responding officer passes the

129 management of the scene to CSI personnel upon arrival. In such instances, an exchange of

130 information shall take place between the officer and the CSI personnel.

131 4.1.3 There are some instances where alteration to the scene prior to CSI response cannot be

132 avoided, including actions for safety and security, or during medical intervention. Any actions

133 taken and any known changes to the scene shall be documented and relayed to those responsible

134 for the investigation.

135 4.2 Arrival Procedure

136 4.2.1 Upon arrival of the first responding LEO(s) to a scene, after reasonably assessing and

137 addressing any threats or risks of harm to prevent additional injuries or loss of life to the public and

138 other responders, shall:

139 a) treat the scene as a crime scene, until determined otherwise.

140 b) make initial observations.

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141 c) make a reasonable attempt to document the identity and contact information of any

142 person(s) at or leaving the scene.

143 d) make a reasonable attempt to document any vehicles leaving the scene.

144 4.3 Safety Considerations

145 4.3.1 LEO(s) shall take reasonable precautions to ensure the safety of all parties, while

146 minimizing changes to the scene. Mitigating actions should include, but are not limited to:

147 a) leaving adequate space for ingress/egress for additional emergency response, should

148 additional emergencies arise.

149 b) contacting appropriate personnel/agencies if hazards such as chemical, radiological, gas,

150 biological, animal, physical, or electrical are suspected or discovered.

151 c) directing additional responding units and personnel to minimize any impact to the scene.

152 d) wearing personal protective equipment (PPE) at all times.

153 e) moving a weapon only when necessary to eliminate the threat of harm.

154 4.4 Medical Intervention

155 4.4.1 The initial responding officer(s) shall ensure that medical attention is provided with

156 minimal contamination of the scene.

157 4.5 Assessing the Scene

158 4.5.1 Assessments shall be made to determine the need for additional resources based on the

159 nature of and extent of the scene(s), including the approximate number of victims/decedents, and

160 apparent injuries. This assessment is a continuous process until the scene is transferred to scene

161 personnel.

162 4.5.2 The responding LEO is responsible for notifying additional units. This may include

163 supervisors and supporting units.

164 4.6 Scene Containment and Control

165 4.6.1 Once an assessment of the scene has been made, responding LEO(s) shall establish

166 boundaries in order to control crowds and / or to restrict access into areas which may have the

167 potential of containing evidence. Movement throughout the scene should be limited to essential

168 personnel only. Do not permit additional LEOs to traverse the scene unless absolutely necessary.

169 The initial responding LEO(s) shall make a reasonable effort to:

170 a) Control all individuals at the scene—prevent individuals from altering/destroying physical

171 evidence by restricting movement, location, and activity, while ensuring and maintaining safety at

172 the scene.

173 b) Identify and record all individuals at the scene, such as suspects, witnesses, bystanders,

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174 victims/family/friends, law enforcement, medical and other assisting personnel.

175 c) Exclude unauthorized and nonessential personnel from the scene (e.g., law enforcement

176 officials not working the case, politicians, media).

177 d) Secure the scene. Set up physical barriers (e.g., ropes, cones, barrier tape, available

178 vehicles, personnel, other equipment) or use existing boundaries (e.g., doors, walls, gates).

179 e) Document the entry/exit of all people entering and leaving the scene, once boundaries

180 have been established.

181 f) Protect the scene. Control the flow of personnel and animals entering and leaving the

182 scene to maintain integrity of the scene.

183 g) Institute measures to preserve/protect evidence that may be lost or compromised (e.g.,

184 protect from the elements (rain, snow, wind) and from footsteps, tire tracks, sprinklers).

185 h) Consider search and seizure issues to determine the necessity of obtaining consent to

186 search and/or obtaining a search warrant.

187 4.7 Evidence Preservation

188 4.7.1 Every item located within the scene should be considered as possibly evidentiary in

189 nature.

190 4.7.2 Physical evidence and scene conditions shall be preserved and left undisturbed to allow a 

191 thorough investigation by scene investigators. Items should not be added (e.g., disposable gloves,

192 food or drink, cigarette butts) or removed from the scene (e.g., weapons or drugs). Exigent

193 circumstances (e.g., weather, perishable evidence) may necessitate early collection or additional

194 preservation steps.

195 4.8 Turning Scene Over to Investigators

196 4.8.1 The initial responding LEO(s) at the scene shall provide a detailed scene briefing to the

197 investigator(s) in charge of the scene. Once a determination has been made to turn the scene over

198 to investigators, the initial responding LEO(s) should concentrate on scene and/or personnel

199 security.

200 4.9 Document Actions and Observations

201 4.9.1 All activities conducted, and observations made at the scene shall be documented as

202 soon as possible after the event to preserve information. The initial responding LEO(s) at the

203 scene shall produce clear, concise, documented information. The following shall be documented:

204 a) Observations of the scene, including the location of persons and items within the scene

205 and the appearance and condition of the scene upon arrival.

206 b) Conditions upon arrival (e.g., lights on/off; shades up/down, open/closed; doors and

207 windows open/closed; smells; ice, liquids; movable furniture; weather; temperature; and

208 personal items.)

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209 c) Personal information from witnesses, victims, suspects, and any statements or comments

210 made.

211 d) The LEO(s) actions and actions of others that alter the scene.

212 e) Any known changes. If it is essential to move items, the original location and state of the

213 item shall be recorded prior to movement as well as who moved the item, why, and to where.

214 f) Any transfer of evidence, through departmental mechanisms for chain of custody.

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215 Annex A

216 (informative)

217 Bibliography

218 1] National Forensic Science Technology Center. Crime Scene Investigation: A Guide for Law

219 Enforcement [supported under cooperative agreements by BJA, NIJ, and NIST]. NFSTC, 2013.

220 2] ISO 21043-1:2018(E) Forensic sciences- Part 1: Terms and definitions.

221 3] ISO/FDIS 21043-2:2018(E) Forensic sciences- Part 2: Recognition, recording, recovery, transport

222 and storage of material.

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