Hotwall - Coldwall Phenomenon in Building Searches
On a warm Las Vegas night a muscular German Shepherd searched through a series of dark offices. His deputy sheriff handler followed cautiously behind. At the end of the hallway the deputy saw a large door. He whistled, pointed his flashlight at the wall on the hinge side of the door and said, “Station.” The dog immediately obeyed by going to the spot of light and laying down. The dog’s eyes were riveted on the handler as he slid toward the door knob. The handler slowly opened the door and peeked inside. He saw a cavernous one room warehouse, 100’ by 150’, with 25’ high ceilings, and a 15’ wide by 12’ high mezzanine running along three walls.
“Damn!’ said the deputy, ‘Now I gotta deal with high ground and a big freakin’ open space. Oh, well, here goes. Okay, Thor, Find’em!”
The dog entered the warehouse and immediately began a swing to his right along the wall. About halfway down the wall his head lifted, as if his nose was pulled by some puppeteer’s string. His head swung from side to side. He stopped panting as he closed his mouth to take in more air through his nose. His pace accelerated as he danced back and forth moving gradually northward and then eastward toward the corner of the building nearest the mezzanine stairs. The dog ran 30’ each way along the north and east walls in a vain attempt to find a way up to the mezzanine. He then concentrated his efforts high in the northeast corner of the building. The dog jumped and climbed in the corner before dropping back to the ground to give the steady, intense bark his handler had come to know as his “alert.”
“What’s your dog telling you?” the back-up asked. The K-9 deputy pointed to the northeast corner of the upper mezzanine and replied with assurance, “That sucker’s up there.” By this time the handler had moved into the room with his back-up. They had taken a position along the east wall, about halfway between the entry door and the mezzanine stairs. The K-9 deputy felt sure the embossing machine between him and the stairs would provide adequate cover if the dog flushed the suspect from the area of the alert. The back-up deputy said, “Look, man, I don’t want to stick my head up there. Why don’t you try to bluff him out?”
“Sounds good to me.” came the reply.
Both deputies hunkered down behind the embossing machine to make smaller targets for whomever the dog had found up there. With pistols drawn, each covered 45 degrees to either side of the corner, preparing for any movement that might come their way. “You! Up there in the corner! Come out now and give yourself up! If you do not come out, I will send up the dog to bring you out.”
“Don’t shoot! Don’t send the dog! I give up! I give up!” came the voice from behind them. The K-9 deputy got that punched-in-the-gut feeling that comes with a sudden rush of fear. As he wheeled to face the voice he saw the man stand up in southwest corner of the mezzanine.
“Damn! . . . ’ said the K9 Deputy, ‘. . . I’m sure glad this was just training. Otherwise I could have been toast.”
At that point I slipped out of my role as back-up deputy talked with the handler as his trainer. “Okay, what just happened here?”
“I just about got myself killed. That’s what. Man, Thor has never been that wrong before. At K9 school they always tell you, ‘Trust your dog.’ Well this sure as Hell is a trust breaker.”
“Hhhhhhmmmm? Why is that?” I asked.
“My damn dog didn’t do his job. That’s why. I trusted him and wound up with my back to the threat.”
“Let me ask you a few questions to see if we can figure out what really happened here. You say Thor didn’t do his job. What exactly is his job in a building search?”
“He’s supposed to find the bad guy.”
“Okay. What’s your job in a building search?”
“Well, duh. My job is to find the bad guy too.”
“Consider this. If two members of a team have different skills, it makes sense to have them each be responsible for what they do best. Thus, there is a division of labor. Your dog’s job is to find the strongest concentration of scent available to him-he’s the detector. Your job is to figure out how the scent is getting from source to where your dog can detect it-you are the analyzer. Together, your job as a team is to find the bad guy. That’s easy if the strongest concentration he can find is at source-the bad guy. Otherwise, you have your work cut out for you. Make sense?” “Yeah, I guess. But, how did that happen? Are you trying to tell me that Thor was right? He indicated on this corner as far away from the bad guy in this room as he could possibly be.” “Time to start doing your job as analyst. Look at my compass for a hint.” The compass pointed to the north wall, not far from where Thor had given his alert. “Think about it. What could have happened outside this building today to affect how scent flows inside it tonight?” “Okay. I think I’m starting to get it now. That bad guy was in an area of warmer air, which carried the scent along the ceiling until it dropped over here in the northeast corner. But . . . why?” He looked around the room and mumbled to himself as he turned a slow circle. The he pointed to the north, east, south and west walls. “Wait a minute. I think I’ve got it. The bad guy was in the southwest corner. It was hot because those south and west exterior walls had more stored heat from sunlight than the north and east walls. I mean the last wall to get direct sunlight is the west wall, and the south wall gets oblique sunlight all day. The north wall gets no direct sun, and the east one has been cooling since around noon. So, heat radiating through the walls warms the air. It rises in the southwest corner and falls in the northeast corner.”
“Excellent!” I said as I pulled out a puffer bottle filled with talcum powder and sprayed a column of talcum dust in the air. “Let’s test your theory. If what you say is correct, there should be a circular flow in this building with air moving away from the cold, northeast corner at ground level.”
“Sure enough. Look at that.” The deputy said as he excitedly grabbed the puffer bottle from my hand and climbed to the top of the rolling ladder left in the middle of the room. “Check it out. The stuff is going from southwest to northeast up here. Just like we figured.”
I hated to dampen his enthusiasm, but for safety’s sake I had to remind the deputy of a few things. “Remember, there are all sorts of factors which will change the air flow dynamic in a room. Can you think of a few?”
“Sure. Open doors and windows. Time of day. Ventilation systems too. I suppose the circular flow effect wouldn’t be so pronounced in a room with walls that were pretty much the same temperature.”
“You’re right. I suppose that’s part of the reason the effect becomes less pronounced with time. I’ve run this scenario over the course of four nights with a total of 42 dogs. By the time the quarry has been up there three or four hours the dogs get their first whiffs of him closer than Thor did. Just the same, all save two have been pulled away by their own noses. This may be as much a factor of time related diffusion of the scent plume as it is a weakening of the circular flow.”
“Good point. I’ve got to remember all this. I mean I feel a lot better, but how am I supposed to know if Thor’s indication is where the bad guy is if or it’s where his scent is drifting?”
“Good question. You can’t know for sure every time, so you have use the division of labor as the foundation of good officer safety. It’s a three step process which starts long before you ever do a real building search. First, begin by training your back-up officers. Teach them they must follow your directions precisely. They need enough faith in you to watch your back at all times, even if you tell them the threat may be in the opposite direction the dog is going. Next, prepare yourself before starting any building search. Try to predict which way the air will flow. Look for exterior and interior walls that differ significantly in temperature. Check for fans, vents, and open windows. Bring a wrist compass and a puffer bottle. Check door seams before you open the doors to determine if they lead to inward or outward breathing rooms. Treat high alerts with extra caution- especially if they come from cold walls since there can be two danger zones with them. Finally, debrief every search. If you will at least use them as opportunities to learn, there is no such thing as a failed application or exercise.”
“Got it. Thor’s got his job, I’ve got mine, and back-ups have theirs.” the deputy said as we walked out of the building. “Thanks, man, that was an eye opener.”
I thanked him kindly as he departed. I must admit I felt a flush of satisfaction as I heard him tell the next handler in line, “You’re gonna love this one, man.”