Tuesday, June 12, 2012

The Case of Preston Hughes III: Marcell's Neck

Color me surprised.


I should have realized this earlier, even as I challenged you with Brain Teaser #2, the one in which I  provided autopsy descriptions of Shandra and Marcell's neck wounds. But you know what they always say: "Blogger, challenge thyself."

In Shandra's Neck, after inserting Preston's knife into the eponymous neck, I concluded that the wound path had to be either front-to-back or side-to-side. The knife could not have been inserted obliquely. This prompted me to send away for the autopsy reports, which the Harris County Institute of Forensic Sciences provided at modest cost and reasonable speed. Shandra's autopsy report made clear that the wound path through Shandra's neck was from front-to-back, slightly to the right, and slightly up.

The wound path through Marcell's neck was more complicated. It was from front-to-back, slightly to the left, and upwards. Notice the lack of "slightly" before the word "upwards". Marcell's injury was definitely three-dimensional, not approximately two-dimensional as was Shandra's.

Marcell's autopsy report provided enough information to estimate the vertical angle of his neck wound. The entrance wound was 7 inches from the top of the head while the exit would was only 4 inches from the top. In other words, the wound path climbed 3 inches from front to back, assuming the victim was in the anatomical position.

The autopsy report also made clear that the wound path distance between the entry and exit points was 4 inches. Sounds like trig time to me. (For the mathematically faint-of-heart, you may want to look away.) The sine of the angle is the rise divided by the hypotenuse. The rise is 3 inches and the hypotenuse is 4 inches, so the sine of the angle is 0.75. The arcsine of 0.75 is 48.6 degrees. Yikes!

Okay, you can look back. The knife traveled upwards through Marcell's neck at approximately a 45 degree angle. Yikes!

I attempted to use Google Sketchup (now Trimble Sketchup) to insert Preston's knife into Marcell's neck at a 45 degree upward angle. As it turns out, that's not as easy as it sounds. I was making my third run at the problem this morning when I realized I didn't need a 3-D model to tell the story. The mismatch between the wound and Preston's knife is so egregious that a 2-D model, such as I used for Shandra's neck, will tell the story just fine.

Here we go. I present below Preston's knife inserted into Marcell's neck.

Preston's Knife in Marcell's Neck

Holy Crap!  The knife looks gigantic. I double-checked and triple-checked my work, and I think I got it right, and it's still difficult to imagine. To get Marcell's neck, I scaled down Shandra's neck based on their relative heights.  Shandra was 65 inches tall and Marcell was only 41 inches tall. (Remember that he was only 3-years-old.) Assuming they were scale models of one another, Marcell's neck should be only 65% as large (in each direction) as Shandra's. I estimated Shandra's neck circumference from her BMI and came up with 13 inches. That means Marcell's neck circumference would have been around 8.5 inches. Measured along one side from front to back, it should be 4.25 inches.

I put white 1/4" markers along the left side of Marcell's neck. It took 16.5 of those markers, and that works out to 4.125".  I call that close enough.

I put four of those 1/4" markers across the knife blade (near its base), and they indicated that the knife is 1" wide. The fill-in ME described the blade width as slightly larger than 1".

It looks to me as if I have scaled the knife and neck properly with respect to one another.

From a properly projected top view, the length of the knife would look shorter than I have shown, by about 30%, due to the upward angle of the wound path. I have not foreshortened the knife, however, because the blade length does not seem to be the issue.

The blade passing through Marcell's neck created both an entry and an exit wound. The wound path length was 4 inches long, so the knife should be longer. The knife blade shown is 5.5 inches long, so the blade length is consistent with the wound path length.

I have shown in red the location of entry wound. I centered that wound at a point 1.5 inches from the front of the neck, as per the autopsy. That would be six 1/4" bars. I made the wound 1 inch wide, as per the autopsy. That would be four 1/4" bars total, two on either side of the center point of the wound.

Look at the wound. Look at the knife. You have to be able to see it. Hopefully I don't need to point out the blindingly obvious.

Okay. Fine.

There is no way that Preston's knife could have made the wound in Marcell's neck. No way.

Preston's knife is way too wide, and now it's absolutely obvious. Preston's knife blade is 1 inch wide. The wound in Marcell's neck was 1 inch wide. That doesn't mean the wound and the knife are consistent. It means they are inconsistent. Preston's knife would create a 1" entry wound only if it went in perpendicular to the surface. If the blade comes in at an oblique angle, then the width of the entry wound will be substantially larger than the blade width.

As you can see from the image above, Preston's knife would have left an entry wound approximately 1.5" wide.

Then I remembered that the knife fit nicely into Shandra's neck, and her entry wound was 1.5" wide.  Here's the money shot from Shandra's Neck.

Preston's Knife in Shandra's Neck

So that explained the difference. Marcell's entry would was only 1" wide while Shandra's was 1.5" wide.

But I was wrong again.

As I was preparing this post, I checked the autopsy report for the umpteenth time. It said Shandra's entry wound was only 1-1/8" wide, not 1-1/2" wide.

How did I get that wrong?

Then I recalled that I wrote  Shandra's Neck before I had access to the autopsy report. Instead, I got the dimensions of the wound from the police report of Officer J. L. Waltmon, who arrived at Ben Taub Hospital just as Shandra's lifeless body arrived. Walton wrote (badly):
Sgt. then view the comps. body and found that she had a stab wound to the left side of the neck. This wound was 1 1/2" wide and 1 3/4" down from the left ear lobe on the left side of the neck.
Officer J. L. Waltmon was wrong, and that caused me to be wrong, and I didn't find my error until just before beginning this post. Shandra's neck wound was not 1.5 inches wide; it was only 1.125 inches wide. Preston's knife could no more have caused Shandra's neck wound than it could have caused Marcell's neck wound.

That is true not simply because Preston's knife was single-edged and the murder weapon was double-edged. It is true as well because Preston's knife is simply too wide to have created either Shandra's neck wound or Marcell's neck wound.

Color me surprised, not just because of what I write here, but because of I intend to write next about Marcell's neck.

Can you see where I'm going with this?

Anon (if I may call him by his first name) noted in the comments that Marcell's neck was more likely close to 10 inches in circumference, rather than 8.5 inches as I had estimated. Anon provided a link to support his claim. I reviewed it and I agree with him that 10 inches is more likely.  I have therefore re-scaled Marcell's neck accordingly an present the resulting image below:

Preston's Knife in a 10" Circumference Neck

Notice that there are now 20 1/4" white bars along the left side of the neck. That's 5 inches for 1/2 of the circumference.

The result remains. The 1" wide knife blade (inserted front to rear) is too wide to make a only a 1" wide entry wound, if that would is oriented at an angle to the blade.

The result, as it turns out, is insensitive to the circumference of the neck. If you look at the recreation of Preston's knife inserted into Shandra's neck (which I calculated to have a 13 inch circumference, and which I displayed again in this post), you will see that the a 1" wide blade is too wide to have created the 1-1/8" entry wound in her neck.

Preston's knife was not the murder weapon. It's 1" wide blade is too large to have created the neck wounds. Also, as explained previously, it was single-edged and the neck wounds were created by a double-edged blade.

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Anonymous said...

I'd wager that Marcell's neck circumference was somewhat larger than 8.5 inches. I haven't read through this post carefully yet (so I don't know how much it matters), but it seems like 10 inches might be a more realistic guess.


tsj said...

Thanks for the tip and the link. I'll update the figure tomorrow. It won't change the conclusion, though. Even on Shandra's 13 inch neck, her 1-1/8" wide entry wound is too small for a 1" wide blade.

Marcell's 1" wide entry wound will be too small for Preston's knife whether his neck circumference is 8.5 or 10 inches.

Anonymous said...

Good stuff, TSJ, keep rolling with it.


xkittenx said...

I know Preston is innocent of this crime the problem is hes on TEXAS DR and as we all no there is only one way off the row Texans love the kill to much to let one go. The police did not do there job here they wanted a open and shut and they did everything they had to do to get one. The fact Preston's knife was tested in the actual court room is ridiculous and when the test shows positive for animal blood and negative for human blood should have shown doubt,the fact the prosecutor explained the result away by saying he washed the knife is laughable and should have been thrown out of court if indeed Preston had washed the knife then surely there would have been no blood trace human or animal... I blame the jury as much as i blame the police in this case how on earth they could send someone to death on the evidence they were given is beyond me.I have tried to get hold of both police officers in this case along with police reports and relevent papers and im stone walled every time.However i now plan to contact mr Hartley know i no where to find him im more convinced than ever that he is indeed not telling all he knows along with his wife and her so called mates,Like yourself i find it hard to believe she would approach or accept a lift from strangers if she had just been frightened like she said she was.Police should be looking closer at Hartley i no i will..

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