Criminal investigators are professionals who are in the business of investigating crimes with the goal of identifying the perpetrator. These crimes can range from misdemeanors to felonies. Their main task is to gather as much information about the crime as possible, as quickly as possible, and then to analyze that information to figure out what evidence exists and what it shows about what happened.

Criminal investigation is an applied science that involves the study of facts about criminal activity. The facts are used to search for and analyze evidence that can ultimately be used in the trial of a suspect. A complete criminal investigation can include searching the places where evidence of crime is thought to be located, interviewing victims, witnesses and suspects, collecting and preserving evidence, and applying various methods of investigation and analysis.

So, for example, a criminal investigator may search a crime scene to see if there are any surveillance cameras that may have filmed the crime scene or the perpetrators in the area of the crime scene. If they find a video that shows people who might have been the perpetrators of the crime in question, they then proceed to try to identify the individuals. If they can identify the possible perpetrators, they can then locate them and interview them.

Who Conducts Criminal Investigations?

Criminal investigations are usually conducted by law enforcement officers. These are the police detectives who work for city and county police departments. Of course, the Federal Bureau of Investigation (FBI) also conducts investigations aimed at identifying the perpetrators of federal crimes and producing evidence for the prosecution of perpetrators by the U.S. Department of Justice.

There are other official federal and state agencies that have the authority to investigate and launch criminal charges. In the United States, these include the Internal Revenue Service (IRS) and the Securities and Exchange Commission (SEC) and the Investigative Services Branch of the National Park Service.

In addition, each state has a state law enforcement agency that investigates crimes defined by state statutes. So, the officers of those agencies who are trained in investigative techniques would also conduct criminal investigations.

What Methods Are Used in Criminal Investigations?

Today’s criminal investigations commonly use a number of modern scientific techniques known collectively as “forensic science.” So, a modern criminal investigation may call upon a number of experts who specialize in such skills as the analysis of DNA, fingerprints, footprints and shoe prints, handwriting, ballistics, and other relevant technologies.

Their tasks involved in conducting a comprehensive criminal investigation include the following:

  • Searching a crime scene effectively, with knowledge about how not to disturb possible evidence at the scene;
  • Analyzing electronic communications, such as cell phone data, to glean what information they can provide;
  • Collecting samples of substances and materials from a crime scene,
  • Submitting evidence for the appropriate type of analysis, e.g. DNA analysis of blood samples;
  • Participating in reconstruction of the crime,
  • Identifying witnesses, then locating them and interviewing them;
  • Obtaining the identification of a suspect by a witness through a line-up;
  • Identifying objects that could be evidence of the crime, locating the objects, seizing them in a way that does not violate the U.S. Constitution or the constitution of the state in which the crime occurred and then preserving the evidence;
  • Identifying a suspect, locating the suspect and interviewing the suspect in a manner that does not violate the U.S. Constitution or the constitution of the state in which the crime occurred.

Most criminal investigators have completed a criminal justice program at one of the many colleges and universities in the U.S. that offer them. Criminal investigators tend to specialize in one particular field, such as homicide investigation or rape investigations. In this way, they master the particular methods that are used in the type of investigation in which they specialize.

In criminology courses, prospective criminal investigators are trained in thinking critically and scientifically, which are essential skills for a good criminal investigator. A good criminology or criminal justice program also teaches its students some of the basic technical skills that they can use as a starting point for further specialization.

Prospective criminal investigators will learn about many different academic disciplines in a criminology program including such topics as psychology, sociology, and various “hard” sciences, such as biology and chemistry.

What Are Some Legal Issues Surrounding Criminal Investigation?

Criminal investigators need to be very diligent in following the law for at least three reasons. They are as follows:

  • Protection of Constitutional Rights: When questioning suspects, it’s essential that criminal investigators ensure that the Miranda Warning has been communicated to the suspect, so that the suspect’s rights are preserved and they can request an attorney if they so choose. In addition, the Miranda Warning must be communicated so that any statements the suspect makes can be used in court.
    • In addition, any other evidence to which a suspect’s statements leads investigators can only be used if the suspect has been properly warned. Investigators should also be sure that they only conduct searches of private property with a valid search warrant or pursuant to an exception to the warrant requirement. They must also seize evidence only pursuant to a warrant or an exception to the warrant requirement;
  • Elements of Crimes: Every crime has elements that a prosecutor must prove in order to convict the perpetrator. For example, the crime of theft comprises a criminal act in which property belonging to another is intentionally taken without that person’s consent. A criminal investigator needs to know and understand this definition and know what evidence needs to be gathered to prove each element;
  • Proper Methods of Criminal Investigation: Many of the processes that investigators must use in an investigation must be used in particular ways in order to be valid.
    • For example, eyewitnesses to a crime may be asked to identify a possible perpetrator through a line-up. In a line-up, 6 or 7 people who resemble the perpetrator are presented to the eyewitness in a line with the perpetrator. The eyewitness views the line of people through a large glass, so the eyewitness is not seen by the perpetrator and the others in line with them.
    • If a line-up is to be effective as evidence, it must be conducted in such a way that it is in no way suggested to the eyewitness who the perpetrator is. Procedures such as line-ups must be done correctly to have value, and investigators must learn about correct methods.

How Can I Become a Criminal Investigator?

Criminal justice programs at colleges and universities teach students the law that is relevant to criminal investigation and the other subjects that an investigator must master to do their job effectively. In addition, federal, state and local governments that hire law enforcement officers have their own in-house training programs.

Job requirements vary depending on the location and the agency. In general, a person who aspires to be a criminal investigator must be a U.S. citizen and at least 21 years old. Because an investigator is usually a member of law enforcement, they must develop and maintain firearms proficiency. So, having a record of felony or misdemeanor convictions may disqualify a person from serving in law enforcement. After being hired, new employees are usually trained in an academy that is specific to the agency in which they are going to serve.

If a person wants to apply to be an investigator for federal agencies such as the FBI, the DEA, the Bureau of Alcohol, Tobacco, Firearms and Explosives, a person must have a bachelor’s degree from a college or university. Studying such fields as law, criminal justice, psychology, sociology and social work, would help a person develop the skills they would need on the job and increase their chances of getting hired.

Some positions might also require work-related experience in law enforcement, or a combination of education and work experience. For example, the FBI requires successful applicants to have at least two years of full-time professional work experience or one year if they have a master’s or higher degree.

Usually, an investigator would spend time on the job and then pursue promotion to an investigator position within their department or agency. The market to become a criminal investigator is very competitive, and reportedly it gives a person an edge to learn to speak foreign language in common use in the U.S. to a high level of proficiency.

Do I Need a Lawyer for Help with a Criminal Investigation

If you have been involved in a criminal investigation as a witness, eyewitness or a suspect and you have questions about law enforcement methods used, you should consult an experienced criminal defense attorney. Your attorney is going to make sure that your rights are protected and that any police investigator proceeds in a way that respects your interests.