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Research: Understanding suspect movement patterns while clearing a building

Is a suspect more likely to go to the blind corner or somewhere else in a room in an attempt to ambush an officer?

Suspect search AP21101708639983.jpg

Members of the Vermont State Police tactical team conduct a search a barn for an assault suspect.

AP Photo/Lisa Rathke

By Hunter Martaindale, Ph.D., and J. Pete Blair, Ph.D.

Your department tasks you with creating training scenarios to practice clearing a building where a fleeing suspect may have run. The suspect doesn’t want to go back to prison so he decides he’s going to ambush any law enforcement officers who come looking for him.

As part of the scenario, your officers will likely perform some sort of threshold evaluation and enter the room utilizing whatever room entry technique your department uses.

While there are many things to consider when setting up scenarios, we’d like to draw your attention to two aspects:

  1. How would you set up the training room?
  2. Where would you have the “bad guy” hide?

At ALERRT, we train officers to perform a threshold evaluation (i.e., slice the pie) from outside the room in order to get eyes on approximately 85% of the room. This allows officers to focus on the 15% of the room that they haven’t seen when they make their entry (see Figure 1).

Blind corner suspect search.jpg

Figure 1. Blind corner in a corner-fed room.

The blind corner exists because of the angles present in corner and center-fed rooms. Some refer to this area of the room as the blind corner, unknown, or hard Corner.

We train a few different room entry techniques that officers could utilize to enter the room and address the blind corner. While we have training that focuses on addressing the blind corner, we also deploy several scenarios where the suspect is located somewhere other than the blind corner.

Through the process of developing and executing different scenarios, we began to wonder if our scenarios were reflective of where a suspect is most likely to go. Specifically, we wanted to know if a suspect would be more likely to go to the blind corner or somewhere else in the room in an attempt to ambush an officer. Essentially, we wanted to know if we were creating accurate training scenarios in terms of suspect placement or if we should adjust according to the data.

Suspect search rooms.jpg

From top to bottom: Room 1, 2 and 3

Blind corner experiment

We set up a series of experiments to address these questions.

In the first experiment, we randomly assigned study participants to one of three rooms. Participants were told to find a hiding spot that they would use to ambush entering officers.

  • Room 1 was completely void of furniture. With nothing in the room, 80% of participants hung around the walls, and 20% floated somewhere in the middle of the room. About 39% of these participants would have been in the blind corner.
  • Room 2 had a single desk placed in the middle of the room. Two-thirds of participants hid behind the desk and about 24% hid in the blind corner.
  • Room 3 had the same desk, but we added a filing cabinet and a small base cabinet on the sidewall next to the door. The majority of participants went to the filing cabinet (65%). With multiple pieces of furniture in the room, only 10% went to the blind corner.

This initial pilot study showed that participants hiding from law enforcement were more likely to choose to hide behind furniture than position themselves in the blind corner. The pilot study was a classic experimental design where each condition was highly controlled.

Furniture vs. blind corner

For the second phase, we wanted to give the participants more hiding options and allow them to actually ambush responding law enforcement officers. Essentially, we wanted to make it more realistic for the participants. In this experiment, we gave participants access to the entire downstairs of our large training building. We wanted to know if they would continue to choose furniture over the blind corner, and also how well the furniture would conceal them from the officers.

The downstairs of our training building is over 3,000 sq. ft. and has six different furnished rooms. Participants were told they just committed a crime and didn’t want to go back to prison. They were given a Glock 17T Simunition gun to engage the responding officers with. They had less than a one-minute head start on law enforcement, and they were to try and shoot the responding officers. Once a participant’s allotted hiding time expired, two law enforcement officers were deployed to find the participant.

Participants hid in a blind corner 34% of the time. Forty-five percent of the time the participants positioned themselves along the wall that is visible from the door, and 21% of the time the participants went in the center of the room. Participants chose the blind corner more often than in the first experiment. This could be because they weren’t simply hiding; instead, they were attempting to ambush the responding officers.

To us, the more interesting results are shown in Figure 2. Participants used some level of concealment 84% of the time. Nearly two-thirds of the time the participant would only be partially concealed (i.e., the officer could see a body part while looking at the furniture). An example of partial concealment would be someone crouched down behind a desk. The individual’s feet and/or legs could be seen from looking directly at the desk. Sixteen percent of the time the participant was fully concealed behind an object. These participants could not be seen by the officer unless the officer physically went behind the object to look. And 16% of the time the participants were in the open waiting to shoot at responding law enforcement officers.


Figure 2. Participant concealment.

Key takeaways

At ALERRT, when we have questions about our training or scenarios, we run experiments. We always strive to have the best, most realistic training experience for our students. We believe this set of studies holds value not only for ourselves but also for a variety of law enforcement agencies as they develop scenarios. As such, there are a few key takeaways from these studies to discuss:

  • Vary where you place the scenario suspect in the room. As these data show, participants were not in the blind corner the majority of the time. For instance, if you focus solely on performing room entries on the blind corner you may develop a training scar and miss a suspect that is partially concealed or is clearly able to be seen in another part of the room. By varying the suspect’s location, you help alleviate potential training scars.
  • Vary the room setup. Eighty-four percent of the time the participants had some level of concealment. Move furniture around to different parts of the room. Challenge yourself to pick apart the room from the threshold in a wide number of different layouts.
  • Practice sound threshold evaluation techniques. Approximately 85% of the room is visible from the door. If the situation allows, spend ample time working the room from the threshold. Approximately two-thirds of the participants were not in the blind corner, and the majority of them were only partially concealed or not concealed at all. Research has shown that officers performing threshold evaluations pick up threats faster and have fewer priority of fire issues than officers who hastily dump into a room (see, Blair and Martaindale – Evaluating police tactics: An empirical assessment of room entry techniques).
  • Consider deploying alternative tactics from the threshold to improve your ability to find a suspect. If you reasonably believe you’ve lost the element of surprise while conducting your search, flashlights can be used to bounce light off of walls, ceilings, or the floor. This process may allow you to bounce light around a piece of furniture and see a shadow. Flashlights can be deployed even when a room is lit. The high lumen output of modern-day lights will still have the ability to cast shadows even in the most lit rooms. Alternatively, the light may elicit a response from the suspect such as shuffling his feet. Any noise made by the individual will alert you to his location. If the suspect is armed and intent on causing harm to officers, we recommend positioning the light as far away from your body as you can. This minimizes the possibility of being struck by gunfire if the suspect shoots at the light.
  • Diligently search behind all pieces of furniture. When you do make a room entry, ensure someone checks behind all pieces of furniture before exiting the room. Sixteen percent of the time the participants were fully concealed and could not be seen from the threshold. After entering the room, officers should communicate and move in a coordinated fashion to clear areas that could not be seen during the threshold evaluation or initial entry.

About the authors

Hunter Martaindale, Ph.D., is director of research at the ALERRT Center at Texas State University. Dr. Martaindale has published multiple reports, peer-reviewed articles and a book on active shooter events and law enforcement tactics. His research predominately focuses on active shooter events, law enforcement tactics and the impact of stress on decision-making.

J. Pete Blair, Ph.D., is the executive director of the Advanced Law Enforcement Rapid Response Training (ALERRT) Center and a professor of criminal justice at Texas State University. He earned his Ph.D. in criminal justice from Michigan State University. He is recognized as a leading expert in the field of active attacks. He has published numerous books, articles, and commentaries on active attacks, police tactics and training. Dr. Blair regularly presents on active attack-related topics to groups across the country and internationally.