Zimmerman Trial: Evidentiary Flashback: AUTOPSY REPORT: Clinical cause of death of Trayvon Martin
It is common knowledge at this point that George Zimmerman fired a single 115g 9mm JHP bullet into the chest of Trayvon Martin the night of February 26, 2012, that the bullet struck Martin's heart, and that Martin died as a result of his injuries. I have obtained a copy of the official autopsy report and examined it for details on the clinical cause of death of Trayvon Martin. (You can review the entire report here in the link at the bottom of this post.) In this post I will summarize the key findings and provide some analysis of those findings.
Disclaimer: I am not a physician. I did my graduate work in molecular biology at Harvard University, and worked as the low guy on the totem pole on my college ambulance crew. I was nowhere near an EMT, but saw plenty of trauma and emergency treatment of injuries. I even got to pick up a dismembered finger one time. And, of course, I've seen my share of forensics reports in the normal course of my legal career. So, that's the background I bring to this interpretation of the autopsy report. Caveat emptor.
Medical Examiner Report & Report of Autopsy
The key summary diagnoses and findings of the autopsy report were:
- Gunshot wound in the left chest, on a path directly front to back
- The path of the bullet (or parts of the bullet) passed through the skin (naturally, as well as the pericardial sac, right ventricle of the heart, and right lower lobe of lung along with bilateral pleural cavity hemorrhage (I'll explain the real-world implications of those medical terms in a moment).
- The bullet fragmented as it passed through the body, into four components: the lead core and three segments of the JHP's cover jacket (only two larger jacket fragments are mentioned in this report, but a very small ~3g fragment was also recovered).
No part of the bullet over-penetrated through the body, so from a terminal ballistics perspective the bullet performed reasonably well. It is generally preferable that the jacket not separate from the core, as the jacket should assist in controlling expansion of the core in a JHP round, but in this instance the jacket fragments would have served to cause additional bleeding injuries and stop hostile actions more quickly, perhaps, than a whole bullet would have.
For more information on the forensic examination of Zimmerman's pistol and ammunition, see here:
On external examination Martin's body seemed perfectly normal for a 17-year-old. He weighed 158 pounds, was 71 inches tall, and had a medium build in apparently good health (other than, of course, being deceased).
It is notable that other than the gunshot wound to the chest, Martin's only other injury was a small 1/4" by 1/8" abrasion on the fourth finger of his left hand. Of course there would have been no swelling from traumatic injury--say, to his knuckles--because his body stopped functioning before any of the body's repair mechanisms could be brought into play.
The organs generally appeared normal, except for the respiratory system, which found both lungs collapsed (more on this in a moment). This is noted both in the text of the report and in the attached sketch--RL (right lung, weiging 210 grams) and LL (left lung, weighing 200 grams) have scrawled beside them "Collapse".
Medical Examiner's Death Report
The medical examiner's death report labels the death as a homicide, indicates that the last person to see Martin (then listed as "John Doe") alive was "G.Zimmerman," and notes that the circumstances surrounding the death were "Shot to chest by known person."
The toxicology screen also noted quite trace amounts of THC and THC metabolites, but nothing near the level one would expect of someone who had smoked marijuana contemporaneously with that night's events.
The report also notes that Trayvon Martin was pronounced dead at 7:30PM on February 26, 2012, at 2831 Retreat View Circle, Sanford, FL, by the Sanford Fire Department.
Medical Examiner's Death Certificate Worksheet
The death certificate worksheet noted the cause of death as "gunshot wound of chest", manner of death as "homicide", and how the incident occurred as "shot by another person."
Immediate Cause of Death: More Likely Respiratory Failure Than Blood Loss
So, given the trauma incurred, we can consider the actual biological causes of Martin's death.
There was, of course, the matter of the injury to the right ventricle of the heart, which caused a very substantial amount of internal bleeding. The right ventricle is responsible for pumping deoxygenated blood through the lungs, and so operates at a considerable pressure. Blood loss would have been rapid and substantial as long as the heart remained beating. Indeed, given the site of injury, deep inside the thoracic cavity, it seems likely that this injury alone must necessarily have proven mortal even if it had occurred with Martin prepped for surgery in an operating room.
But is that blood loss from the right ventricle the direct and immediate cause Martin's death? Certainly, blood loss will cause death if the quantity lost is sufficient--for a person of Martin's size, death would typically occur at about the point where 3 liters of blood had been lost.
The autopsy, however, did not reveal that much blood loss. Rather, only about two liters of blood were were found within Martin's body (and, given the nature of the injury and the relatively rapid onset of death, the overwhelming majority of blood loss would have remained internal). Two liters of blood loss is more than sufficient to cause loss of consciousness, but probably not death in someone Martin's size.
The problem, it seems, was not so much with the volume of blood lost, but with where the blood was lost to.
Here it's important to understand the role of the "pleural cavity". Your lungs need to be able to move inside your body, expanding and contracting as you breath. To allow this movement to be free and without obstruction from other organs and tissues in the body, the lungs are wrapped in twin layers of tissue, the visceral and parietal pleura, in between which is a fluid. Imagine two layers of plastic with a thin layer of lubricant between them, and how slippery they would be against each other, and you can see how they would allow easy movement of an object on one side relative to an object on the other side. The space between these two layers is referred to as the "pleural cavity".
(Incidentally, the heart, which must of course also move inside the body, has a similar arrangement, called the pericardial cavity).
We've probably all heard the phrase "collapsed lung," before, but may not be familiar with what the term is intended to describe, biologically. The lungs must be able to both expand and contract in order for respiration to occur. They do so within the pleural sac just described. If, however, the pleural sac fills with something other than lung--a liquid, say, or even air at atmospheric pressure--the lung can readily contract, but then finds it can no longer expand. This is what is meant by a collapsed lung.
In Martin's case, something did fill up the pleural cavity, for both lungs--two liters of his blood, pumped at high pressure from his right ventricle. The displacement of volume caused by this blood was more than sufficient to cause both lungs to collapse, as revealed at autopsy, preventing continued respiration and oxygenation of the blood.
It seems likely, then, that the immediate cause of Martin's death was respiratory failure, as a consequence of lung collapse induced by internal cardiac hemorrhage into the pleural cavity.
Had the blood been somehow flowing from his body, rather than being retained internally, it is virtually certain that Martin would still have died once his blood loss exceeded 3 liters--which it certainly would have done, given that there was no means by which an EMT crew was going to be able to stop hemorrhage from a breached right ventricle.
You can view the original Medical Examiner's and Autopsy Report here: trayvon.martin.autopsy