TRACKING IN BLOOD
(Reflow into Edges)
RECAP: A previous article, TRACKING IN BLOOD (Reflow Into Voids), described simulations which showed that when a pool of new blood (a pool that is less than 2 minutes old) is stepped into, the pool will reflow and largely obliterate the void created by the footstep. When a pool of old blood (more than 22 minutes old) is stepped into, the liquid is stiffer, less prone to reflow, and most of the void is retained, remaining visible after the liquid has dried. Insofar as the final left footstep void as Simpson left the scene of the crime is still visible on the front walk in front of Nicoles chest, it is indicated that Simpson stepped into the pool when it was not entirely fresh 20 minutes or more after the blood started to flow. This finding is consistent with a scenario in which Simpson made an after-the-fact visit and stepped in the main blood pool much after the blood started the flow; it is not consistent with a scenario in which he himself did the crimes and left in two minutes or less after Nicoles throat was slashed.
CRIME SCENE INDICATIONS: In this article we consider the slightly different situation of the final right footstep as Simpson left the scene. That went into the north edge of the blood pool on the first step. The hydrodynamics of reflow could possibly be different exactly because the shoe landed on the edge of the pool, not entirely in the middle of the pool as in the previous experiments.
Figure 1 [DEAR_02A.JPG] is a crime scene photo of the first step from William Dears book. The blood pool on the first step is conspicuous and an arrow labeled B points to the void where Simpson appears to have stepped to stain his right Bruno Magli shoe upon exiting the place. An earlier stride analysis (One Man, One Trip) led to the conclusion that Simpson stained his left foot at the front walk blood pool at A in Figure 2 of Tracking in Blood, Reflow into Voids. That same stride analysis also explained the only east-pointing footprint (on the second step) as due to Simpsons tentative and unwitting step into the first step pool upon arrival, and then his withdrawal of that foot. So, the void at B in Figure 1 is interpreted as being due to two steps, one as Simpson left, and the other as he arrived.
The situation is shown more explicitly in Figure 2 [DEAR_02C.JPG]. Here the outline of the Bruno Magli shoe is shown in blue pointing west, as Simpson exited; a region on the edge of the step, south of and adjacent to the heel, is where Simpson is presumed to have stepped on arrival (with the toe portion of the shoe only, on the edge of the step.) Remember that when Simpson was at the scene the steps were in profound shadow, and he could not see the steps, what was on them, or even his own feet. He had to proceed down those steps pretty much by feel.
EXPERIMENTAL METHOD: As before, the basic idea was to pour latex paint on a concrete stepping stone, wait a period (2 minutes to simulate new blood, 22 minutes to simulate old blood), step in the paint, photograph the result, wait 30 minutes, and photograph the result again. As before, the paint was shaded from the direct sun when it was not being poured, stepped in, or photographed. However, some factors were changed.
The unpatterned work shoes used in the earlier experiment were replaced with a pair of new Italian dress shoes bought for the purpose. This is the Ventorini brand (size 12W) with a fine diamond pattern in the sole and half of the heel. The front and back of the shoe is shown in Figure 3 [P056.JPG]. Although this pattern is much different than the Bruno Magli brand, it was considered an improvement to have a shoe with some pattern.
Another significant change was in the technique for stepping in the pool. Previously, I stood a couple of feet back from the pool, reached out with my foot, slammed it into the pool, waited half a second, and withdrew the foot to the original position. (I have referred to that technique as stomp and withdraw.) This time I attempted to simulate the actual steps of Simpson in the Bruno Magli shoes. (Fortunately, I am about Simpsons height and weight, and wear the same size shoes.) I have previously shown the paths of the feet in Figure 1 of Reflow into Voids. I laid out a plastic/paper tarp on the back lawn, put the stepping stone in the middle of that, set a stepladder to one side from which to take photographs, and pasted markers on the tarp to show where the left and right feet should go when tracing through Simpsons series of footsteps. One of these steps is aimed at the right edge of a paint pool to be spread on the stepping stone. I have called this technique in which I attempt to trace Simpsons actual footsteps, Step and Continue. There were differences in the splash and spray produced by these two techniques, as will be reported in a subsequent article.
Figure 4 [SPLSH403.JPG] shows the setup for a trial where a step in the whole pool, rather than the edge, was intended. A set (2/22 minutes) of trials into a complete pool with the left foot was done in experiments #54 and #55; trials into the edge of a pool with the right foot were done in #56 and #57. The shadow of the photographer on the ladder in Figure 4 is conspicuous.
RESULTS: Figure 5 [E57.JPG] shows the result of stepping on the edge of a pool two minutes after it was poured. By comparison of the photos taken at individual times of the process, it was possible to draw colored lines showing the extent of the pool then. The purple line shows the shape of the pool just before it was stepped into. The yellow line shows the shape of the stain just after the step (at 2 minutes). This line encloses a region within which the tile is stained with a thin film of liquid. To the left of the region is the full depth pool, to the right is the unstained tile. The blue line shows the extent of the full depth pool 30 minutes after the step. Notice that the heel area is completely filled in by reflow, and the sole area is mostly filled it. In fact, reflow has covered some areas that were not covered before the footstep.
Figure 6 [E56.JPG] shows a similar situation for experiment #56, in which the paint was allowed to set for 22 minutes between the time it was poured and the time it was stepped into. A similar significance of purple, yellow, and blue lines is intended. In this case, the heel void is only slightly filled by reflow as is the sole void. Because my photography was done in bright direct sunlight (as contrasted Rokhars work at Bundy in indirect shaded light) some of the subtleties are lost in the pictures of my experiments. There is only a suggestion of a mottled film in the void of my step, whereas it is rather clear in his picture of Figures 1 and 2. However, to the eye, and especially when the specimen was moved into the shade, the void areas in my experiment did have the thin and patchy appearance of the void on the first step at Bundy.
CONCLUSION: The characteristics of reflow when the edge, rather than the center, of the pool are stepped into are the same as for stepping into the middle. That is, a step into a young (less than 2 minutes) pool will largely reflow and fill the void, a step into an old (more than 22 minutes) pool will largely retain the void.
Furthermore, the range of conditions of these experiments shows that this conclusion is valid for many specific circumstances
* For temperatures from 63° F. to 85° F.
* For a variety of shoes ranging from old work shoes with unpatterned sole and heel to new dress shoes with patterned bottoms.
* For a variety of stepping technique, both a deliberate and forceful stomp and a simulated step.
* Regardless of whether the foot lands in the middle of the pool or on the edge.
The one consistent factor that influences the degree of reflow is the length of time that the pool sits before the foot steps into it. When the step occurs early, in the first 2 minutes after the pool is formed, reflow of the pool will largely obliterate the void; when the step occurs later than 22 minutes after the pool is formed, most of the void from the footstep will remain permanently in the dried pool.
Insofar as voids in the blood pools, consistent with the size and shape of a shoe print, are seen where a stride analysis shows that Simpson stepped as he exited the vicinity of the bodies, these experiments indicate that Simpson stepped in the pools when they had been standing for more than 20 minutes. That is consistent with his having made an after-the-fact visit to the scene, but it is not consistent with the idea that he fled immediately after the victims were murdered.
(Crime scene pix show Simpson stepped in blood pools more than 20 minutes after they formed.)
Dick Wagner Van Nuys, CA (5/16/02) F_PRINT3.doc