OSAC 2022-N-0025, Standard for Scene 

Response: Initial Response by Scene Investigators

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OSAC 2022-N-0025

Standard for Scene 

Response: Initial 

Response by Scene 

Investigators

Crime Scene Investigation & Reconstruction Subcommittee

Scene Examination Scientific Area Committee (SAC)

Organization of Scientific Area Committees (OSAC) for Forensic Science
OSAC 2022-N-0025, Standard for Scene 

Response: Initial Response by Scene Investigators

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OSAC Proposed Standard

Standard for Initial Response at 

Scenes by Scene Investigators

Prepared by 

Crime Scene Investigation & Reconstruction Subcommittee

Version: 2.0

August 2022

Disclaimer:

This OSAC Proposed Standard was written by the Organization of Scientific Area Committees 

(OSAC) for Forensic Science following a process that includes an open comment period. This 

Proposed Standard will be submitted to a standards developing organization and is subject to 

change.

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

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

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

companion publications.

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

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

equipment, instruments, or materials are necessarily the best available for the purpose.
OSAC 2022-N-0025, Standard for Scene 

Response: Initial Response by Scene Investigators

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Foreword

This	document	provides	standards	for	those	who	respond	to	scenes	for	the	purpose	of	conducting	

field	investigations	in	recognizing,	preserving,	documenting,	and	collecting	items	of	potential	

evidentiary	value.		This	document	should	be	utilized	in	conjunction	with	local	regulations	to	inform	

or	augment	applicable	policies.	

This	document	does	not	detail	the	actions	taken	by	crime	scene	personnel	during	the	course	of their	

investigation	or	reconstruction	of	the	scene.	This	document	makes	the	distinction	between	the	first	

responding	law	enforcement	officer(s)	at	a	scene	and	the	response	of	the	investigative	personnel.

This	document	has	been	drafted	by	the	Crime	Scene	Investigation	and	Reconstruction	

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

through	a	consensus	process.

All	hyperlinks	and	web	addresses	in	this	document	are	current	as	of	the	publication	date	of	this	

standard.

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

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

Keywords:	Crime	scene,	response,	Crime	Scene	Investigator,	scene	investigator
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Response: Initial Response by Scene Investigators

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Table	of	Contents

1						Scope.......................................................................................................................5

2						Normative	References............................................................................................5

3						Terms	and	Definitions............................................................................................5

4						Requirements..........................................................................................................6

4.2			Arrival	at	the	scene..................................................................................................7

4.3			Safety	Considerations.............................................................................................7

4.4			Scene	Containment	&	Control...............................................................................8

4.5			Legal	Considerations.............................................................................................8

4.6			Assessing	the	Scene................................................................................................9

4.7			Documentation.......................................................................................................9

4.8			Scene	Processing....................................................................................................9

Annex	A	(informative)	Bibliography.....................................................................................10
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Standard	for	Initial	Response	at	Scenes	by	Scene	Investigators

1		 Scope

This	document	applies	to	the	initial	response	of	scene	investigators,	however	named,	but	commonly	

referred	to	as	crime	scene	investigator	(CSI),	who	responds	to	a	scene	for	the	purpose	of	conducting	

field	investigations	and	undertakes	one	or	more	of	the	following	tasks	in	relation	to	scene	

investigation:	document,	search	for,	identify,	collect,	interpret,	and	preserve	evidence.		This	

document	addresses	the	activities	and	actions	required	of	a	scene	investigator	when	responding	to	

a	scene	and	the	steps	to	be	completed	prior	to	conducting	a	scene	search.

2		 Normative	References

ANSI/ASB	Guiding	Principles	for	Crime	Scene	Investigation	and	Reconstruction.	

ANSI/ASB	Standard	for	Initial	Response	at	Scenes	by	Law	Enforcement.

See	Annex	A,	Bibliography,	for	informative	references.

3		 Terms	and	Definitions

For	purposes	of	this	document,	the	following	definitions	apply.

3.1

contamination

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

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

as	cross-contamination.	(ISO	21043-1)

3.2	

crime	scene	investigation

CSI

A	scene	investigation	that	involves	a	potential	criminal	act.

3.3

crime	scene	investigator

CSI

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

that	involves	a	potential	criminal	act.

3.4

law	enforcement	officer	(LEO)

Any	public	employee	whose	duties	primarily	involve	enforcement	or	investigation	of	laws.
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3.5

personal	protection	equipment	(PPE)

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

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

3.6

scene

A	place	or	object	that	is	subject	to	and/or	requires	forensic	examination.	(ISO/FDIS	21043-

1:2018[E])

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

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

3.7

scene	investigation

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

value.	[Guiding	Principles]

3.8

scene	investigator

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

[Guiding	Principles]

3.9

scene	preservation

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

within	the	scene.	[Guiding	Principles]

3.10

staging	area	

An	area	designated	to	be	used	to	contain	and	deploy	resources	and	conduct	briefings.

3.11

walk-through

An	initial	visual	inspection	of	a	crime	scene.

4		 Requirements

4.1			 ANSI/ASB	Standard	for	Initial	Response	at	Scenes	by	Law	Enforcement details	the	

responsibilities	of	the	initial	responding	law	enforcement	officers.	The	first	responding	scene	

investigator	shall	ascertain	what	steps	were	taken	by	the	responding	LEO	to	preserve	the	scene	in	

order	to	maintain	the	integrity	of	the	scene	until	designated	crime	scene	personnel	are able	to	

respond.	The	scene	investigator	shall	seek	information	regarding	any	actions	taken	and	any	known	

changes	to	the	scene	prior	to	the	arrival	of	the	scene	investigators.		Prior	to	arrival,	if	the	LEO	

notifies	the	responding	scene	investigator	that	conditions	exist	in	the	scene	that	could	compromise	

the	integrity	or	value	of	evidence,	the	responding	scene	investigator	shall	advise	the	LEO	what	

mitigation,	if	any,	should	be	performed.		The	scene	investigator	shall	participate	in	a	briefing	with	

the	responding	LEO	upon	their	arrival	to	the	scene.
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4.2			 Arrival	at	Scene

4.2.1	 The	scene	investigator(s)	should	obtain	or	have	access	to,	at	a	minimum,	the	following	

information:

a) The	initial	responding	and	primary	LEO’s	names,	agencies,	agency	identifications	

(e.g.,	 badge	number),	and	times	of	arrival.

b) The	primary	authority	for	the	scene	(i.e.	which	agency	is	taking	lead	on	the	scene).

c) The	time	of	the	original	incident,	if	known.

d) The	conditions	of	the	scene	at	the	time	of	LEO’s	arrival.

e) The	size	and	extent	of	the	scene	including	the	existence	of	known	secondary	

scene(s).

f) How	long	the	scene	has	been	controlled	and	any	information	about	access	or	interference	

with	the	scene	prior	to	it	being	controlled.

g) Any	information	regarding	any	alterations	(e.g., items	moved,	disturbed,	or	removed)	to	

the	scene	and	any	movement	of	items	at	the	scene	between	the	arrival	of	the	initial	

responding	LEO	and	the	arrival	of	the	scene	investigator(s).

h) Any	information	concerning	hazards	at	the	scene.

i) Information	from	the LEO	pertinent	to	executing	the	scene	examination.

NOTE	Attention	should	be	taken	to	mitigate	potentially	illegitimate	biasing	information.	

4.3			 Safety	Considerations

4.3.1	 The	scene	investigator(s)	shall	take	reasonable	precautions	to	ensure	their	safety	

while	minimizing	changes	to	the	scene.	Mitigating	actions	shall	include,	but	are	not	limited	to:	

a) Ensuring	the	provision	of	designated	personnel	for	scene	security	and	personal	safety	

for	all	present.

b) Requesting	assistance	from	appropriate	personnel	or	agencies	if	hazards	such	as	

chemical,	radiological,	biological,	animal,	physical,	or	utility	(e.g.	electrical	or	gas)	are	

suspected	or	discovered.

c) Wearing	appropriate	personal	protective	equipment	(PPE)	at	all	times.

d) Taking	periodic	breaks	for	rest	and	sustenance,	especially	if	wearing	PPE,	when	

outdoors,	or	during	long	periods	of	time	on	scene.		
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4.4			 Scene	Containment	and	Control

4.4.1	 The	scene	investigator(s)	shall	review	the	boundaries	established	by	the	initial	

responding	LEO	in	order	to	determine	whether	the	existing	physical	barriers	are	adequate	or	if	

alterations	are	required.	The	boundaries	shall	enclose	the	furthest,	immediate	physical	

evidence	connected	with	the	scene.		Movement	throughout	the	scene	should	be	limited	to	

essential	scene	investigation	personnel	only.

4.4.2	 The	agency	controlling	the	scene	shall	establish	documentation	of	all	personnel	

entering	or	exiting	the	scene	including	the	time	of	their	arrival	and	departure	and	their	reason	

for	entry.		Upon	arrival,	if	such	documentation	has	not	been	started,	the	scene	investigator	shall	

cause	the	process	to	begin.		This	log	should	not	be	the	responsibility	of	those	personnel	tasked	

with	processing	the	scene.

4.4.3	 The	scene	investigator(s)	shall	ensure	that	a	path	for	authorized	personnel	to	enter	

and	exit	the	scene	has	been	established	and	is	appropriate	for	the	preservation	of	evidence	

integrity.

4.4.4	 The	scene	investigator(s)	shall	ensure	that	a	staging	area	is	designated.	The	staging	

area	may	be	located	in	any	secured	area	(e.g.,	vehicle,	trailer,	tent,	or	within	a	building).	The	

staging	area	should	be	positioned	outside	of	present	or	potential	hazard	zones	but	close	

enough	to	the	incident	to	maintain	command	and	deploy	response	resources	in	an	efficient	

manner.

4.4.5	 The	scene	investigator(s)	shall	establish	an	area	designated	for	trash,	e.g.	biohazards,	

other	hazardous	materials,	and	used	supplies.	If	it	is	not	practical	to	place	this	within	the	

staging	area,		an	area	shall	be	carefully	chosen	within	a	confined	portion	of	the	scene.	If	this	

area	is	established	within	a	scene,	the	scene	investigator	shall	ensure	the	designated	area	has	

been	documented,	searched,	and	deemed	safe	to	assume	that	role.	All	items	secured	therein	

shall	be	confined	to	the	area,	contained	within	an	appropriate	receptacle,	and	collected	upon	

departure	from	the	scene.

4.4.6	 The	scene	investigator(s)	shall	establish	a	secure	area	on	scene	for	the	temporary	

storage	of	evidence	following	initial	collection	in	accordance	with	preserving	evidence	integrity	

and	chain	of	custody.

4.5			 Legal	Considerations

4.5.1	 The	scene	investigator(s)	shall	conduct	themselves	with	the	expectation	that	their	

work	may	be	used	in	every	step	of	the	legal	process,	and	therefore	shall	ensure	that	they	

comply	with	applicable	legal	standards	including	those	of	search	and	seizure.

4.6			 Assessing	the	Scene

4.6.1	 The	scene	investigator	shall	conduct	a	preliminary	scene	evaluation	that	should	

include	initial	observations	and	information	obtained	from	the	responding	LEO(s)	to	determine	

appropriate	resources	and	response.
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4.6.2	 The	scene	investigator	shall	conduct	a	scene	assessment	(also	known	as a	“walkthrough”)	using	appropriate	precautions,	to	obtain	an	overview	of	the	entire	scene,	identify	any	

hazards	or	threats	to	scene	integrity,	and	ensure	the	protection	of	physical	evidence,	unless	

doing	so	would	compromise	safety	or	the	potential	evidence.		The	assessment	should	

encompass	time,	conditions,	life,	property,	personnel	and	any	pertinent	information	relative	to	

the	incident.	

4.6.3	 The	scene	investigator	shall	use	the	scene	assessment	to	develop	a	plan	for	the	

coordinated	identification,	collection,	and	preservation	of	evidence.		The	plan	should	be	

reassessed	as	appropriate	to	address	such	things	as	new	information,	changes	in	scene	

conditions,	and	new	material	located	at	the	scene.	This	includes	the	consideration	of	the	

existence	of	multiple	scenes.

a) Measures	shall	be	instituted	to	preserve	and	protect	evidence	that	may	be	lost	or	

compromised	due	to	environmental	conditions	or	the	nature	of	the	evidence	item.	Such	

measures	may	include	prioritized	collection	or	use	of	protective	measures	that	also	prevent	

contamination,	tampering,	alteration,	or	loss	of	evidence.

b) There	may	be	the	need	for	immediate	documentation	and	collection	of	evidence	prior	to	the	

full	completion	of	the	scene	assessment	to	prevent	contamination,	alteration,	or	loss	of	

evidence.

4.6.4	 The	scene	assessment	shall	also	be	used	to	determine	the	need	for	specialized	

reconstructive	efforts	or	additional	resources.	

4.7			 Documentation

4.7.1	 The	scene	investigator(s)	shall	document	all	pertinent	information	and	observations	

including	but	not	limited	to	the	conditions	of	the	scene	and	the	investigative	steps	taken,	

providing	a	permanent	record.	

4.8 Scene	Processing

4.8.1 Information	gathered	during	the	initial	scene	response	and	assessment	shall	determine	

the	actions	taken	by	the	scene	investigator	in	processing	the	scene.		The	information-gathering,	

observation,	and	assessment	processes	are	cyclical	and	shall	be	repeated	and	revised	as	necessary	

throughout	the	entirety	of	scene	processing.
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Annex	A

(informative)	

Bibliography

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

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

https://www.nist.gov/sites/default/files/documents/forensics/Crime-Scene-Investigation.pdf1

2]	Federal	Bureau	of	Investigation.	Standard	ERT	12-Step	Process.	Undated.2

3]	ISO	21043-1:2018(E) Forensic	sciences- Part	1:		Terms	and	definitions,	2018.3

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

and	storage	of	material,	2018.4

1 National	Forensic	Science	Technology	Center.	8285	Bryan	Dairy	Rd	#125,	Largo,	FL	33777

2 Federal	Bureau	of	Investigation,	935	Pennsylvania	Avenue	NW,	Washington,	DC	20535

3 International	Organization	for	Standardization,	1,	ch.	de	la	Voie-Creuse,	Case	postale	56,	CH-1211	Geneva	20

4 International	Organization for	Standardization,	1,	ch.	de	la	Voie-Creuse,	Case	postale	56,	CH-1211	Geneva	20