Intro to Criminal Investigations (Reading Assignment)

The word “investigation” derives from the Latin word “vestigare”, which means “to track or to trace”.

Criminal investigations as they are today are a fairly new concept. In the past, crimes were solved by lewd and discredited means i.e. witchcraft, torture, and other various methods. Then in the early 19th century criminologists felt there was a need to create specific standards to identify criminals. This was due in part because criminological theories would be useless unless the correct person(s) were prosecuted. For example, the theory of deterrence and positivist theory of rehabilitation cannot be correlated to a person(s) who is not guilty because no amount of punishment can fix an innocent person(s). Therefore, Dr. Hans Gross, Edmond Locard, and August Vollmer took on the task of developing and creating the earliest crime lab in the world, to develop and nurture the art and science of investigation.

However, a criminal investigation is not specifically used in just law enforcement. For example, a Loss Prevention professional might conduct criminal investigations into Organized Retail Crime. A Private Investigator might investigate Workman’s Compensation Fraud. By asking questions and performing certain tasks it leads you to an end result whether it be an arrest, conviction, or the loss of benefits, investigation is the start of it all.
When using investigation in conjunction with law enforcement, it is safe to say that a crime cannot be solved on its own unless the police or investigator conducts a criminal investigation.

A criminal investigation is “the systematic, step-by-step process of determining whether or not a crime has been committed, and if so, who committed it”. Since this process involves a step-by-step process, it may help to know the different stages included in the development of an all-out criminal investigation. These are:
1.   Detection- is the fact of discovery. It is the circumstance at random that triggers the process of our criminal justice system. This happens when a crime or activity is noticed by the police or is brought to their attention.
2.   Preliminary Investigation- is the initial stage of the investigation immediately after the crime has been committed.
3.   The preliminary investigation portion is usually carried out by first responders or first officer(s) on the scene. These folks take on the following vital responsibilities on site: a.   deal with emergencies b.   neutralize any threats on scene c.   administer aid to anyone injured d.   cordon off crime scene to help preserve any possible evidence e  record all information and convey it to available patrol units for possible pursuit f.   wait for detectives and relay information
4.   Follow-up Investigation- this step happens after the completion of the preliminary investigation. It is a more in-depth investigation usually made by detectives or investigators. This stage is implemented to help combine and tie up any loose ends of the initial investigation to help compile the strongest case possible for prosecution.
5.   Re-investigation- in some cases is resorted to whenever critical errors have been committed or are suspected from the earlier investigation which may hinder the closure of the case. This usually occurs when unethical investigative practices are suspected, thereby requiring reinvestigation to prevent a miscarriage of justice. These unethical investigative practices may include: a.   Torture b.   Planting evidence c.   Instigating
6.   Frame-up – where a non-guilty individual is made to appear guilty of a criminal act committed by someone else
7.   Whitewash or cover-up – is when police officials deny that a crime was committed

Criminal investigations in any stage are repressive. Meaning it is only used when criminal activity happens. Crime prevention is the primary purpose of law enforcement. However, if the primary purpose fails then criminal investigation takes over. Which makes criminal investigation reactive instead of proactive. A criminal investigation can also fall into a preventive category in a very limited sense. By conducting a thorough investigation, law enforcement can prevent future crimes from being carried out by the same individual.


Not all law enforcement officers are an acceptable fit for a detective or investigative role. To qualify for such assignments candidates must possess competent Intellectual, Emotional, and Physical characteristics

Intellectual: To be a proficient investigator one must be able to differentiate between facts and fiction since they will be dealing with numerous kinds of information. One must learn how to use deductive and inductive reasoning, implement and maintain a logical process of elimination, familiarize oneself with the general knowledge and motivations of criminals, and be proficient at asking probing questions. One must do all of these things all while being able to retain information. On top of this, one must prepare his/her report in a well-organized case folder.

The investigator also has the initial responsibility to propose what offense to charge. One, therefore, must have a profound knowledge and understanding of the penal laws in his/her specific state/city/county. An investigator is also expected to be proficient on the correct procedures for the filing of a complaint, Application for Search Warrant, testimony in court, making affidavits, etc. Also, one must be able to identify the evidentiary value of materials and information he/she comes across in the course of his/her investigation. All of these require more than an average intellectual capability.

Emotional/Psychological: Investigators often come across cases which expose the worst of human nature everything from: molestation from a family member, children murdering their parents, neighbors stealing from neighbors, rapists/serial killers who ravage and kill their victims. Investigators who have insufficient emotional and psychological experience may find themselves affected by the cases they are handling. If things get too personal for an investigator, he loses his neutrality and objectivity by becoming too involved in the case. An emotionally immature policeman may be susceptible to manipulation. Remember, not all complainants are victims. For instance: subject A complained that she was raped by subject B. Human nature naturally feels sympathy for A, the “victim”. But the investigator cannot be swayed so easily. He/she must be suspicious of the possibility that subject A is lying and was motivated by outside influences against subject B. Therefore, a good investigator must be impartial and have the diligence and professionalism to independently gather facts.

Physical: the least important but still valuable characteristic is the ability to continuously work long hours in the field under less than favorable conditions. Detectives often find themselves working in remote areas where there is limited access to food, drinks, and medicines. There are instances where the location of the crime scene is physically challenging such as a ravine, cliffs, or a deep well where the investigator may have to climb up and down or in or out of. Not all but most crime scenes are exposed to the elements, the sun, the rain, chemicals and even infectious bacteria. This can hinder the investigator’s ability to do his/her job safely.

CSI EFFECT- is a phenomenon in correlation to criminal investigation that results to an “unrealistic expectations of the public in the conduct of criminal investigation” due primarily to the popularity of fictional TV shows such as CSI. Far from the romanticized depiction of detectives on televisions and in the movies, effective investigators are often involved in hard work, risking their lives and limbs, and living anonymously far from the limelight’s
often depicted in the movies.

Goals of Criminal Investigation

The objectives of a criminal investigation are not as simple as just solving cases. Occasionally, a case is unsolvable, yet every lead must be exhausted. A criminal investigation is an art and a science. In science, the absolute truth is often achieved. Experience has shown that in criminal investigations a less decisive hypothesis may sometimes be all that is possible to achieve.

The objectives of criminal investigations are as follows:
1.   Determine if a crime was committed.
2.   Collect information and evidence legally to identify who was responsible.
3.   Apprehend the person responsible or report him to the appropriate civilian police agency.
4.   Recover stolen property.
5.   Present the best possible case to the prosecutor.
6.   Provide clear, concise testimony.

(3 I’s of investigation)
The following are recognized tools of investigators:
1.   Information
2.   Instrumentation
3.   Interrogation

INFORMATION – For purposes of investigation, information is “anything that tells us something, whether, correct or incorrect”. This is a generic term that refers to any facts, statements or materials surrounding a crime that has been committed. If the information good and solid and could further advance the investigation, it is called a LEAD. When no more leads can be developed, it is said that the investigation is facing a BLANKWALL.

SOURCES OF INFORMATION The following are sources of information:
A. Persons
B. Places
C. Things

A. Persons– these are individuals who may be:

1. Victims– the direct recipients of the crime itself who suffered direct or indirect loss/injury as a consequence thereof
2. Complainants – persons who informs the police of a crime
3. Witnesses– third party persons who have personal knowledge of relevant facts surrounding a crime
4. Informers/Informants– furnishes information relative to a crime either voluntarily or for a consideration
5. Suspects – person who is accused as the perpetrator of the crime

In processing persons as sources of information, the investigator generally conducts an:

INTERVIEW – is a general conversation for the purpose of gathering as much pertinent information as the person(s) can possibly give. However, when the person(s) is the suspect or a hostile witness, the conversation is rather confrontational and is called INTERROGATION. With respect to the suspect, interrogation is only acceptable if made in compliance with Miranda Rights (we will get to these in a different section).

Planning the interview: the interviewer must have a basic knowledge of the crime before any intelligent questions and elicit useful information can be obtained from the interviewee. General data must be gathered. This data involves the basic 5W and 1H of criminal investigation:
1.   What?
2.   Where?
3.   When?
4.   Who?
5.   Why?
6.   How?

Assuming that a crime was reported and you are the criminal investigator. On-site you must establish the following facts:
1.   What is the nature of the case?
2.   Where was it committed?
3.   When did it happen?
4.   Who are the persons involved?
5.   Why did it happen?
6.   How was it committed?

B. Places – as a source of information generally refers to the scene of the crime (locus criminis). It is important for the investigators to determine the location of the actual crime scene because it contains the highest concentration of physical evidence and possible witnesses.

Crime scenes may be:
1.   Primary Crime Scene – the place where the crime was committed
2.   Secondary Crime Scene – the place where the crime was continued
3.   Pseudo Crime Scene – a crime scene staged to mislead, cover-up, or conceal what really happened

C. Things – are any objects found at the crime scene or in the suspect’s possession. These objects are of evidentiary value. The investigative classification of evidence is more technical and is somewhat different from the classification of evidence under the Rules of Court.

Things include the following:

1. Trace evidence – evidence found at the crime scene which places the suspect on the scene such as fingerprints, shoe imprints, and cigarette butts. Trace evidence may also include evidence which indicates the whereabouts and movements of the suspect, such as plane tickets, ATM withdrawals, receipts, etc.
2. Associative evidence – evidence found in the suspect which places him at the crime scene, such as bite marks, tools, & blood-stained shirts.

There are also special types of associative evidence called:
1. Souvenir – part of the crime scene which the suspect intentionally took as a remembrance, such as the underwear of a rape victim
2. Trophy – part of the body of the victim which the suspect intentionally took as a memento, such as the pubic hairs of the rape victim.

For criminal investigations to be successful, the investigator must understand the general rules of evidence; provisions and restrictions. Law enforcement investigators must also be familiar with the laws and limitations as well. As investigators adopt a more scientific approach to criminal investigations and rely heavily on tangible evidence than on the confessions of suspects or eyewitness accounts, the relationship between the investigator and criminologist becomes critical to the success of the investigation.

Most criminal investigations begin at the actual site or location in which the incident took place (scene of the crime). It is important that the first officer on the scene properly protects the evidence. The entire investigation rests on the initial law enforcement officer being able to properly identify, isolate, and secure the scene. Crime scenes should be secured by establishing a restricted perimeter. The purpose of securing the scene is to restrict access and prevent evidence destruction. There are many factors that dictate how a crime scene should be protected.

However, nationally recognized standards for crime scene protection suggest the following three-layer or tier perimeter:
∞   An outer perimeter (established as a border larger than the actual scene to keep onlookers and nonessential personnel safe and away from the scene).
∞   An inner perimeter (allows for a command post and comfort area just outside of the scene).
∞   The core (actual scene).

Investigators conduct systematic and impartial investigations to uncover the truth. They work to determine if a crime was committed and to discover evidence of who committed it. Investigators efforts are focused on finding, protecting, collecting, and preserving evidence discovered at the crime scene or elsewhere. Their professional knowledge and skills should include crime scene photography, development of latent fingerprints, and recording crime scene impressions. They are skilled in the techniques and methods used to interview witnesses and interrogate suspects.

Law enforcement investigators document their actions and relevant details of an investigation in an investigator’s notebook and use various methods of crime scene photography and sketches to capture the facts of a case. They ensure that evidence is accounted for by maintaining a complete chain of custody to allow it to be admissible in court. They must be skilled in providing professional testimony. An investigator’s charter is to find impartially, examine, and make available evidence that will clear the innocent party and prosecute the guilty party. As fact finders, investigators maintain unquestionable integrity during a criminal investigation.

Law enforcement investigators frequently perform drug suppression, surveillance, and undercover operations. These operations are designed to gather critical information and police intelligence and stop illegal drug and contraband traffic. Investigators network with other police and intelligence agencies to report and share information.

Less experienced investigators can gain valuable experience by reviewing cases, consulting with peers, and working with experienced investigators. They also expand their knowledge through law enforcement courses designed to teach nationally recognized investigative techniques.

A Realistic View of Investigative Activities


Conducting a successful investigation is often the result of having a wide range of knowledge and using common sense. There are certain actions that apply to all investigations. Investigators follow these intelligent and logical steps to ensure that an investigation is conducted systematically and impartially. Over time certain actions have proven useful for specific investigations. It is an intelligent investigator who understands and applies the knowledge, skills, and techniques learned for a particular investigation and uses them wherever they are most useful in any investigation. This means that, in order to conduct a successful homicide investigation for example, the investigator must do more than just follow the investigative process and guidelines for investigating homicides. Knowing and using a technique usually used for investigating a robbery may be just what is needed to help solve a homicide case.


To achieve success in any case, is always a function of intellect and experience. Develop a hypothesis that serves as the framework for the case to set the basis of how the case investigation will flow. The hypothesis is based on a survey of the crime scene. It is a reasoned assumption of how the crime was committed and the general sequence of acts that were involved.


You may find that you must change the hypothesis as new facts and leads are uncovered. Investigators must overcome the tendency to make contradicting information fit a set of existing assumptions. For example, if there is evidence that a murder was committed at the place where the body was found, it is enticing to ignore a factor a lead that does not fit that assumption. The lack of some item or event is just as important as its presence. As an investigator obtains new information, he must be willing to modify or change his initial ideas about how a crime was committed. Only through constant reassessment can the full value of his experience be realized.


The art of an investigation lies primarily in gathering and evaluating information and evidence, both testimonial and physical. Testimonial evidence, like sworn statements of eyewitness accounts and admissions of guilt, is obtained through interviews and interrogations with people. Physical evidence, like-identified weapons, fingerprints, imprints, and blood, for example, is obtained by searching crime scenes, tracing leads, and developing technical data. Investigators must always be evidence conscious. The scene of any crime is evidence in and of itself, as is the testimony of trained investigators regarding observations and findings. Both physical and testimonial evidence are vital to the successful prosecution of an investigation.


Obtaining testimonial evidence requires skillful interpersonal communication (IPC) with human sources of information, primarily with the persons directly involved in a case. Questioning victims, witnesses, complainants, suspects, and sources is the investigative method most often used to obtain testimonial evidence. It is also the method used to obtain background information that gives meaning to the physical evidence collected. The solution to many crimes is the direct result of leads and testimonial evidence developed through interviews and interrogations.

All law enforcement personnel must be skilled in IPC to elicit useful information. They must know how and when to ask the “right” questions. An investigator’s attitude and method of questioning, as much as the questions asked, can elicit the leading information and testimonial evidence needed to bring an investigation to a successful conclusion.

Victims and witnesses are questioned to gain information that will help show the facts of the crime. Investigators should do the following:
1.   Question victims and witnesses to gather information on what they saw, know or did in regards to an offense.
2.   Question sources for information pertaining to the case under investigation.
3.   Ask questions to obtain observations and develop descriptions that will identify suspects.
4.   Question suspects to remove suspicion from the innocent and give the guilty an opportunity to confess.
5.   Record information obtained from interviews and interrogations. From this information, develop statements that may become documents admissible in court as evidence when sworn to under oath and signed by the swearer.


The successful outcome of a case depends on an accurate evaluation of the evidence. Evaluation of evidence begins with the first information received about the occurrence of a crime. Evaluate evidence in light of the situation and conditions found at the crime scene and the information obtained by questioning persons connected with the event. Each piece of evidence should be evaluated individually and collectively in relation to all other evidence. If doubt exists about the evidentiary value of an item, process and secure it as evidence for later evaluation. Then an investigator can determine the worth of the item as evidence to the investigation.

After evaluating evidence and statements of expected testimony gathered during the preliminary investigation, decide what facts are still needed to establish the proof needed for the offense being investigated. Coordinate with other agencies to gain the information or documents needed to support the investigation. Make sure the administrative action is started early to secure help from and refer undeveloped leads to others agencies. Take early action to give other agencies time to comply with requests. Exploit every available local source of information while awaiting replies or action.

Carefully use selected sources and seek out reliable persons who possess information that is material to the case. The information needed can often be obtained from a central location. If new information is found, ensure that it is widely disseminated.

Evaluate evidence again in light of all new information. Support the evaluation with common sense and sound judgment enhanced by your experience. Discuss the evaluation of the evidence with supervisors, other investigators, technicians, other experts in a given field. Continue this evaluation process until the investigation has been concluded. Prepare a final report to document the findings when an investigation has been completed. The report must reflect the who, what, where, when, why, and how of the offense. A final report must be a thorough, timely, and objective evaluation of the findings.

The Result of Investigative Activities


After doing everything we discussed above, the investigator now shifts to case preparation, which is loosely defined as “the gathering of all records of the case in an orderly, chronological and logical manner, before the filing of the complaint”.

These records consist of the following:
1.   Affidavits of complainant and witnesses
2.   Affidavit of arresting officers (in case of entrapment or warrantless arrests)
3.   Initial or spot report
4.   Progress reports
5.   Crime laboratory examination results
6.   Closing or Final report which contains the recommendations of the LEAD investigator and endorsement by the Chief

Police Reports – are the official record of the actions taken by various police personnel in relation to an event, incidence or crime.

1. Initial or Spot report – made immediately after an incident. Usually, within 24 hours. Usually made by patrol officers or first responders.
2. Progress reports – contains a brief of actions taken after the initial investigation. Usually, criminal cases involve several progress reports which the lead investigator collates alongside the initial report and other documents; and
3. Final or Closing Report – contains a run-through of all the findings, reports, documents and affidavits and well as the recommendations of the lead investigator. Unlike progress reports, there can only be one final report.

Characteristics of a good report: The quality of your work as an investigator is judged by the quality of your report. Ideally, a police report must be like a bikini – short enough to make it interesting, yet broad enough to cover the most interesting parts. The following characteristics are desirable in a report:

Keyword: FACTUAL
1. Factual & Objective – the report must be based on facts and must be free of conjectures, speculations or opinions
2. Accurate – the information contained in the report must be precise
3. Concise & Complete – Concise means the report must be as short as possible, direct to the point and not circuitous. Complete means the report must contain all the elements of information (5W’s & 1H)
4. Timely – the report must be submitted on time
5. Unadulterated – the report must not be embellished. Statements made by the witnesses
must be recorded in “full” without adding or subtracting from what the witness said, even if the investigator believes that the statement made by the witness is wrong. Your job is to record it, not to edit it
6. Analytical – the report must develop one unified theme culled from all the different sources of information
7. Legible – the report must be written that others can read and understand its content, especially if the report is handwritten. This is important, as handling officers may be assigned in a different jurisdiction, retire, or may become unavailable so that other officers who assume the investigation must be able to continue the work of the previous investigator.


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