Criminal investigations: An overview for new detectives
The one fundamental component critical for effective police investigations is thoroughness
I have been asked by Police1 to produce an article series that delves into criminal investigative procedures and best practices. Unlike Sherlock Holmes, who could ostensibly divine absolutely anything from only a cursory inspection, real-world investigators have to resort to more mundane strategies to accomplish the job and solve the mysteries of crime.
The one fundamental component critical for effective police investigations is thoroughness: The more details an investigator overlooks the less likely they are to find the whole truth of the matter. The most effective way to avoid the likelihood of a mistake of omission is to create a list and check things off as you move along.
Between 1983 and 1994, I worked as a homicide detective with the Miami-Dade Police Department (MDPD) in Miami, Florida. I left in 1994 when I was promoted to police sergeant and re-assigned. Throughout my time there, the Detective Bureau devised a checklist that was amended through the process of trial and error. The list enumerated each notification a detective would make from the moment they were assigned as lead investigator in a case.
The list included a basic lineup of who to contact: chain-of-command, the medical examiner’s office, the crime scene unit, the prosecutor’s office, the police union representative (in the event of a police-involved shooting) and other ad hoc entities that may be needed for that particular crime scene, such as canine, divers, aviation and bomb unit. The list was essentially a “to-do” list for a detective responding to the scene. The list also included an outline of investigative steps that could be of aid throughout the investigation.
Not all crimes will entail a high-profile response with myriad investigative and support resources at your disposal. Home and commercial burglaries or robberies, for example, may not require such preparation or effort, but a check-off list is still highly recommended.
Setting boundaries with crime scene perimeters
Once at the scene, depending on the parameters (indoor or outdoor scene), your first responsibility is to establish the nature and scope and then ensure proper scene security. As a rule, operate on the side of caution: It is easier to bring ropes in on an area that was initially secured than it is to expand the ropes after much of the outer scene has been trampled.
Handle scene security proactively: A scene security officer, usually a uniformed officer, is responsible for maintaining access and egress. Typically, that officer will maintain a “scene contamination log” that includes the name and badge number or other identifiers for anyone who is accessing the interior scene.
Ideally, your scene has an interior perimeter, that area wherein a person is likely to come into direct contact with evidence, and the outer perimeter, where you stage non-essential personnel like command staff or support staff. In a perfect world, you would also designate a remote area where you can more or less corral the media on scene into one place.
Gathering and investigating the evidence
Upon arrival, photograph all items of evidentiary value in situ without any external items like markings or brightly colored cones. The scene and all evidence should be initially photographed or videotaped in their pristine condition before any interaction between police and the scene is initiated.
A detective from the investigative unit should be assigned to oversee the actual crime scene investigation as it is processed by the crime scene technicians. The latter are experts at identifying, memorializing, collecting and transporting evidence; however, they may not be privy to many of the overarching investigative priorities of that particular case.
For example, I had a murder at a housing project in Miami where two competing drug dealers ran through the projects, shooting at each other as they ran. One was killed; the other fled the scene. We had hundreds of feet of blood spatter on a walking path that ran through the interior of the projects.
We asked crime scene techs to collect a swab every 10 feet along the length of the blood trail. While they did not immediately know why we insisted on such an arduous and tedious task, it became obvious when we were able to identify both the victim and the killer’s blood at different points along the same path.
Canvassing for information and witnesses
A thorough area canvass can be a great source of information, as well as a means to protect the integrity of your investigation. Take area canvasses seriously: Anyone interviewed should be identified and questioned about what they did or did not hear, see and know.
Document these findings in detail. If someone does not answer the door, make a note of it, and go back at a later time to identify and interview them. Document – in detail – what they did or did not witness and whether they were home at the time. Some of these same individuals could be swayed by money or out of fear to later render false testimony on behalf of a defendant. Being able to impeach them from your canvas interview could become critical to the prosecution.
Even if someone claims not to have been home, document it and ask where they had been at the time. A good area canvas can serve not only to produce witnesses but to eliminate suborned perjury in the future by negating those opportunities through the ability to impeach false witnesses.
Any witnesses identified on or near the scene should be separated (if possible, isolated) in a police vehicle or by other means to avoid interaction with each other or bystanders. Such interactions could inadvertently affect the witnesses’ recollection of events.
People are easily swayed to believe altered facts if prompted. Investigators should allow witnesses to fully answer and volunteer information, but the investigator should also control the Q&A to ensure an efficient flow of relevant and probative testimony. Statements should be sworn and memorialized, either digitally (audio/video) or recorded via stenography.
Take detailed notes as you proceed. Being able to reflect on what you have done or failed to do can give you the advantage of correcting any omissions before you take down your scene and move back to the office to continue your investigation.
Leveraging photos and the “Big Brother” era
Given the Orwellian world we live in today, it is remarkable how many detectives or investigators turn a case over to prosecutors only to be reminded that they failed to ask about a Ring home security camera or other audio/video surveillance. In many instances, by the time you turn over the case to prosecutors, any video footage that likely existed will have been taped over or erased. So, ask while on the initial scene.
When it comes to incriminating evidence, nothing is more compelling than a video of the defendant committing the crime. Also, remember to take a lot of photographs of interior scenes – macro (general) to micro (specific). You never know what you might notice later in one of the photographs that you missed during your on-site inspection of a scene.
As you proceed with your investigation, things that did not seem relevant at the scene may become highly important to the prosecution. It is nice to have a pictorial record of that scene to refer to during trial preparation.
A match for Sherlock Holmes
As an alternative to the highly developed deductive prowess of Sherlock Holmes, for the rest of us, let it suffice that we prepare, outline and remain thorough in our investigative processes. Errors of omission can become the source of failure; however, with a modicum of preparation, we can cover every base, cross every “t,” and dot every “i.”