A Falling Blood Drop



    IMPROMPTU EXPERIMENT
: The other day I was bringing in a load of firewood and snagged myself on the thorn of a pyracantha branch (back of the middle of the proximal phalanx of the right ring finger). My instinct was to wash it off and stop the slow flow of blood, but on the way to the kitchen I wondered if there were not some pending Simpson case experiments for which this would be useful. Ahh. I have always wondered about the appearance of a drop of blood fallen from the fingertip of a hand on a limp hanging arm. I retired to the back concrete walk to wait for the flow to find its way to the end of my finger and fall.

    Once that was done, I could see that the wound might be good for a couple more drops and I got out the tape measure. The height of the first fall was 30". I stood in a slouch to let the second fall, and it fell 26" before it hit the concrete. I was patient, and there was one more drop; for that I stood in a stoop, and it fell 21". (While I waited for the blood to trickle, I experimented with different postures, and found that it is credible that a skulking man, creeping away from something he did not want to be seen near, could assume a posture in which his fingertip was only 9" from the ground.) After the third drop I marked the concrete with pencil notations of the height of fall of the drops, washed up, and got the camera. As it was getting dark, I attached the flash, and documented the drops.

    RESULTS: The results are shown in the first figure [BLD_DROP.JPG]. bld_drop.jpg (164766 bytes)White spots within the drop are apparently artifacts from the flash; they do not appear in the drop as seen with the eye. As expected, the resulting pattern is an irregular approximation to a circle, with ragged edges. As the height of the fall increases, there are progressively seen "rays" emanating from the spot; this is sometimes referred to as "splatter." In the case of the highest fall there are also detached jots of blood not connected by a ray to the main body.

    The results are summarized:

    30" FALL: 9x10mm spot; maximum contiguous ray 4.5mm beyond spot; most distant unconnected jot 12 mm from edge of spot.
    26" FALL: 9x9mm spot; maximum contiguous ray 3 mm beyond spot; most distant unconnected jot 8mm from edge of spot.
    21" FALL: 7x8mm spot; maximum contiguous ray 1.5mm beyond spot; no unconnected jots.

    Taking as an "index of splatter" the ratio of the length of the maximum contiguous ray from the center of the spot, to the radius of the spot, one sees...

    30" Fall: Splatter = 190%
    26" Fall: Splatter = 167%
    21" Fall: Splatter = 137%

    SIMPSON'S BLOOD DROPS: Now, the reason that this is of interest is that it has been claimed that the five drop trail at Bundy did not show splatter, and hence those drops did not fall from the fingertips of a 6 foot man, erect. To better understand this allegation, I sought out some pictures of the Bundy blood drops and found several. Two were from court TV, and I show the more distinct of them here as "DROP_115.JPG".drop_115.jpg (58494 bytes) This is a TV image of a photographic enlargement presented in court. The aspect is a little oblique, the object of interest is a small part of the frame, and it has the fuzziness and lack of definition characteristic of a TV picture. It appears that there is a little bulge on the top of the blood spot, and another on the bottom, otherwise there is no hint of splatter. A critic of the prosecution case that was relying on this could well believe that there was no splatter in the 5-drop trail.

    But, there is also the photograph at Goldberg, p. 242+2 (bottom), which shows the blood drop at evidence item #114, and is here reproduced as "DROP114.JPG". drop114.jpg (210977 bytes)This photograph (not TV image) clearly shows about a dozen rays reaching out from the blood spot, although they are thin threads, somewhat different than the rays in my experiment. Also, there are not little jots of blood conspicuous in Simpson's drop, as there are in mine. However, these differences could be accounted for by differences in the mechanical properties of his blood from mine (chiefly viscosity) and a difference in the concrete surface onto which the drops fell. (My back walk is of medium roughness, Nicole's walk was probably smooth.)

    I can't determine the actual dimensions of the Simpson drops, but on one printout the drop has a diameter of 22mm, and the longest ray extends 9 mm from the edge. This gives an "index of splatter" of 182%. If this drop had the same characteristics as the drops in my experiment, this would relate to a 6 foot man walking with a slight slouch.

    Furthermore, there is also a photograph in Goldberg at p. 242+3 (bottom) which shows a blood drop from Simpson's driveway. This is not disputed to have been shed by Simpson as he was walking on his own property, and it shows even less splatter than the Bundy drop.

    CONCLUSION: There is nothing in the appearance of the Bundy blood drops -- when they can be clearly seen -- to cause a person to doubt that they fell from the finger at the end of a hanging arm of a 6 foot tall man, such as Simpson.

Dick Wagner • Van Nuys, CA (1/23/01) NG_708.TXT

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