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Policy & Procedure Page 1 of 6
Lexington Police
Department
Subject: Preliminary Investigations
Policy Number:
41I Accreditation Standards:
Reference: 42.1.4; 42.2.1; 42.2.3 Effective Date:
12/1/10
New
Revised
Revision
Dates:
1/24/19
By Order of: Mark J. Corr, Chief of Police
GENERAL CONSIDERATIONS AND GUIDELINES
The ultimate success or failure of police efforts in solving a case is often based upon
the immediate police response and preliminary investigation. This is generally the
responsibility of patrol officers who are nearly always the first officers on the scene of
a reported crime. It is the patrol officer who will initially discover facts, locate and
identify witnesses and preserve physical evidence that is relied upon by the police
investigator in the subsequent follow up and search for the suspected criminal.
The purpose of this policy is to provide guidance to those officers who conduct
preliminary investigations.
It is the policy of the Lexington Police Department that:
Preliminary investigations shall be conducted on all incidents which violate the
criminal code of the Commonwealth or town bylaws, or have the potential to
result in foreseeable criminal or civil action; and
All officers understand and comply with the following procedures when
conducting initial investigations of crimes.
PROCEDURES
A. Responding to a Crime Scene
1. Officers proceeding to a crime scene shall be vigilant and watchful in their
approach for any signs of:
a. Suspicious activity that may be related to the crime;
b. Evidence of a fleeing criminal;
c. Persons acting suspiciously or furtively in the vicinity; or
d. Objects being thrown from a vehicle leaving the scene.
2. A threshold inquiry is justified when officers observe an individual fleeing
from the scene of a crime.i
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3. Responding officers shall record or report the registration numbers of any
suspicious vehicles coming from the scene and the general description
and any obvious characteristics of the operator or occupants if possible.
4. Officers shall be alert for any additional messages from the dispatcher.
a. The dispatcher shall immediately furnish the responding officers with
any supplementary information that would be of assistance to them.
b. The dispatcher shall provide any available information that would
indicate the possibility of a dangerous situation or the possible
presence of an armed or dangerous criminal.
B. Preliminary Investigation
1. Assignment of Investigating Officer [42.1.4]
a. The patrol officer arriving at the scene of an incident will usually
be responsible for initiating and conducting the preliminary
investigation unless otherwise directed by a supervisor.
b. A responding detective may relieve a patrol officer of the
preliminary investigation if directed by a supervisor. Generally, a
detective at the crime scene does not relieve the patrol officer of
the responsibility to conduct the preliminary investigation.
c. When a crime scene or investigation is turned over to a detective,
all information obtained up to that point, and the identity and
location of any physical evidence discovered, should be relayed
to the detective.
2. Assessment [42.2.1(a)]
Upon arriving at the scene, the officer shall observe all conditions
present, make note of the events that have taken place and make record
of remarks made at the scene relevant to the situation. After this initial
quick assessment of the situation, the officer shall report as much of the
following to the dispatcher as soon as practicable:
a. Assessment of any injured persons, providing or summonsing
appropriate medical aid;
b. The nature of the crime committed;
c. As complete a description of the offender as possible and the
direction of his/her flight;
a. Whether the offender is, or may be, armed and dangerous;
b. A description of any vehicle being used by the offender and of any
occupants of that vehicle;
c. A description of any firearms or other weapons used in the
commission of the crime;
d. A description of any property stolen and whether it may be in the
possession of the offender;
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e. Any additional information that may lead to the apprehension of
the offender;
f. The need for additional assistance from responding officers or
detectives; and
g. The need for assistance from other agencies or special services
(e.g., fire department, ambulance, etc.).
h. The names address date of birth and other personal identifiers as
may be required under the report writing policies or practices of
the department.
3. Arresting the Perpetrator
a. If the perpetrator is at the scene, the crime is an arrestable
offense, and probable cause to arrest exists, the officer may make
an arrest. For further information, see Department policy 41A-
Arrest. In determining if an arrest is appropriate, the officers
should consider:
i. The nature of the crime;
ii. The suspect’s propensity to violence;
iii. The age of the suspect;
iv. Suspect’s criminal history;
v. The suspect’s likelihood to default; and
vi. The need for further investigation.
b. When deciding whether or not to leave the scene to pursue a
perpetrator the following factors should be considered:
i. The likelihood that an apprehension can be made;
ii. The physical condition of the victim(s);
iii. The need to protect the victim from a renewed attack;
iv. The potential danger to the public if the perpetrator is
allowed to escape;
v. The nature of the crime committed;
vi. The time and place of occurrence;
vii. The lapse of time between the crime and the arrival of the
police at the scene;
viii. Whether the suspect is known to the officer or a good
description of the offender is available;
ix. The availability of other officers to conduct the pursuit and
to apprehend the offender.
x. The need to preserve evidence & monitor witnesses.
4. Preserving Evidence [42.2.1(c)]
a. A critical task for the first officers at the scene of a crime is to
protect the crime scene for the preservation of any physical
evidence. Officers shall prevent as little contamination as
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possible. (See Department policy 83A-Collection and
Preservation of Evidence.)
b. Major crime scenes shall be maintained in the same manner as it
was left by the perpetrator, as far as possible.
i. Clear the largest area possible. Investigators can condense
the size of the scene area if necessary.
ii. Secure and isolate the actual crime scene.
iii. Secure a larger area for police personnel conducting the
investigation.
iv. Begin a “Crime Scene Sign-in Sheet,” recording the name,
agency, date and time of all persons entering the inner
crime scene.
c. Witnesses and other persons connected with the crime and
persons associated with the property or premises involved in the
crime shall be told to remain present and available for questioning
but shall be removed from the actual crime area.
d. Officers shall look for any item of evidentiary value. This includes
but is not limited to the following:
i. Weapons, shell casings, tools, clothing, shattered glass,
stains, footprints, fingerprints, tool impressions, tire
markings, etc.;
ii. Ordinary objects or articles found in unexpected or unusual
locations;
iii. Ordinary objects or articles having individual peculiarities or
markings;
iv. Uncommon objects or articles not generally found at the
location of the particular crime; and
v. Bits and pieces of evidence, which may be of minor
importance individually, but when taken together, can be of
significant value to the investigation.
e. The location of physical evidence shall be noted, but the evidence
itself shall not be moved or touched if detectives or evidence
technicians are responding to the scene to recover evidence. If
evidence is to be recovered by officers at the scene, or if it is
absolutely necessary to ensure preservation of evidence, follow
these procedures: [41.2.1(c)]
i. Photograph the item prior to moving it if possible.
ii. Carefully note its exact location and position at the scene.
iii. Handle the item using gloves and in such a manner as to
prevent any alteration of its condition or the accidental
impression of fingerprints.
iv. For further information, see the Department policy 83A-
Collection and Preservation of Evidence.
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5. Interviewing Complainant, Witnesses and Suspects [42.2.1(d)]
a. The purpose of a preliminary interview is to obtain as much basic
information as quickly as possible in order to identify the
perpetrator and to establish the basis for the follow-up
investigation.
b. Officers shall attempt to locate, identify and interview reliable
witnesses. [42.2.1(b)]
i. Obtain the name, address and contacted information for all
witnesses.
ii. Separate witnesses to prevent them from discussing what
has occurred among themselves before they are
interviewed. This may taint individual recollections.
c. Conducting Interviews [42.2.1(d)]
i. The officer may ask each witness to write out a statement
on a voluntary statement form, which describes what
occurred.
ii. Interview each witness separately and in a quiet area if
possible.
iii. When interviewing suspects, be mindful of any obligations
to provide the suspect with Miranda warnings or record the
interview. For further information, see Department policies
41J-Interviewing Victims & Witnesses & 41K-
Interrogating Detainees & Arrestees.
d. Provide information about victim and witness assistance,
including what to do if the suspect or suspect’s companions
threaten or otherwise intimidate the victim or witness. See
Department policy 55B-Victim/Witness Assistance.
e. Provide them with a case number and a means in which to contact
the reporting officer if they recall additional information at a later
date.
f. Neighborhood Canvass
i. After all witnesses are located at the scene have been
interviewed, officers shall canvass residences and
businesses in the area.
ii. Additional officers may do this while witnesses are being
interviewed.
iii. A canvass may identify a witness who may be reluctant to
come forward, a person who may have witnessed
something and does not realize the potential value of their
observations or may locate additional crimes committed in
the area.
6. Report Writing
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a. The officer conducting a preliminary investigation shall make an
accurate and complete written report of the incident in accordance
with departmental procedures.
b. Each Report shall be assigned a case number for documentation
and tracking purposes.
c. An officer making a preliminary investigation should make a
written record of the following data:
i. Date and time of arrival at scene;
ii. Weather conditions and visibility, including the location and
distance from the nearest street light or artificial lighting and
whether the lights were on, if applicable;
iii. Approximate time of commission of the crime and who
discovered it;
iv. Identity of other police officers present;
v. All necessary information concerning any physical evidence
discovered;
vi. Name, address and contact information of victims and
witnesses;
vii. It may be helpful to record the means of identifying a
witnesses (i.e. Mass License, verbal, etc.).
viii. The identity or the best available description of the criminal
suspect or suspects, particularly noting any unusual
characteristics;
ix. The best available description of any vehicle used by the
suspect or suspects;
x. Any information relating to others assisting at the scene
including:
(a) Detectives on scene;
(b) Officer who took photos;
(c) The name and affiliation of any media photographer
who took pictures;
(d) The name and address of any private individual who
took pictures;
(e) The name and address of any individual turning
evidence over to the police; and
(f) Measurements made at the scene and a rough crime
scene sketch if appropriate.
xi. The time and location of any interviews of the victim or
witnesses and a brief statement as to what they heard or
observed; and
xii. Any other information that the officer believes may be useful
for the apprehension of the criminal suspect and his/her
subsequent prosecution.
i Illinois v. Wardlow, 120 S.Ct. 673 (2000).