Crime scene investigation is a critical step in the criminal justice process. It provides the framework that allows law enforcement, forensic specialists, and legal authorities to coordinate their efforts in a manner that supports the rule of law and enables justice for victims of crime. It also establishes the standards that ensure all case elements meet the burden of proof necessary to secure convictions in court.
The seven steps of police investigation differ depending on the type of crime, but some key factors remain constant. For example, whether it is an indoor burglary or a homicide, officers must always begin with a primary assessment of the crime scene. This is followed by the collection of evidence that can be used to build a case against the suspect or victims.
Physical evidence is often collected by investigators using gloves to preserve fingerprints and limit contamination, but it can also be sent to labs for analysis. Forensic experts will also look at trace evidence, like blood, hair, and fibers, and electronic evidence such as cell phone data or web searches. All evidence must be documented with an unbroken chain of custody to prevent tampering or destruction.
Once detectives have collected a large enough amount of evidence, they will interview suspects or witnesses. This is where the skills of trained interrogators come into play. Investigators need to understand human behavior and body language to gain the trust of those they interview and to get a confession. These interviews must be conducted within strict legal guidelines, such as by giving the suspect his or her Miranda rights.