What Do We Know About Forces Necessary To Stab Oneself?

Written by | October 27, 2015 13:26 | 2 responses

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When it comes to looking for the truth, I tend to relay on science, I know what people are gonna say, science doesn’t equal truth but this is the best tool we have, right? Will we ever know how the universe expand, how life appeared on earth, how exactly the brain functions thanks to science? I don’t know, but we are trying our best to get there and I take science over any other explanation because it works most of the time, because it is repeatable, and because it is based on solid evidence…. it is the best method we have to get to the truth.

One aspect of the Elliott Smith’s case that is always ignored is the forensic aspect of stabbing yourself in the chest twice considering the force necessary to do so. There is a good reason why it is ignored, there are not a lot of studies about this, it is very poorly examined and that’s why psychologist experts and other people have free field to express all kinds of hypothesis about the state of mind of a person determined to stab himself… This is why people continue to have no problem accepting that a man with a history of depression and drugs and under some stress could do that to himself, while ignoring the science behind self stabbing.

I want to ignore vague psychology analysis, it’s too subjective for me, I am talking about science, physics, hard stuff and forces measured in newton! This came back to me after a discussion with a forensic behavioral psychologist who contacted me regarding Elliott’s case and wrote this:

‘My reason for asking concerns the depths of the purported injuries.  A “typical” kitchen paring, steak, or other utility knife–even a bread knife–has an average blade length of 3-4″. With the amount of force it takes to self-inflict a knife wound to the chest, the wound depths of Smith’s injuries definitely lead me to question the self-infliction hypothesis.  His wounds are more reminiscent–especially in the presence of two separate penetrations–of wounds inflicted by another person. Two quick jabs to the chest–which would seem supported by the apparent defensive wounds to the arms.

If self-inflicted, the amount of force required to penetrate the chest cavity would cause the knife to be thrust much more deeply–it would not be unreasonable to see a wound at full blade-depth (3-4″).  It’s also less reasonable to assume that someone who just sustained a self-inflicted wound to the chest would have the strength to remove the knife and stab himself again.’

According to the autopsy report, the blade of the knife who killed Elliott was 8” long, more than the average 3-4” the expert was proposing before reading the autopsy report.

What do we know about forces necessary to stab oneself? Not much actually, because these cases are extremely rare. I found the studies of Dr Sarah Hainsworth, an engineer at the University of Leicester, who has been investigating the sharpness of knives as a murder weapon, because the ease with which a blade penetrates the human body has become an important consideration in court cases. The lack of convincing research in this area was posing a problem for the criminal justice system, and if you wonder why this could be useful, here is an example: ‘In one [case], the weapon was relatively blunt and the prosecution barrister argued that because it was blunt, considerable force was used, and that influenced the sentence.’ She explained to the Guardian. This woman knows everything about the biomechanics behind stabbing, and obviously her study only concerns murder (I was not able to find anything related to suicide by stabbing in her study) because, of course, suicide by stabbing is extremely rare. ‘In her experience, the kitchen knife is the weapon most commonly used in murders.’… ‘Murder by knife has been the most preferred form of murder in the last few years,’ she says.

According to a few studies also conducted at the University of Leicester, like this thesis by Dr. Gary Nolan (‘Quantification of forces involved in Stabbings’), we now know a few important things. In a 2004 research project, it was determined that the tip of a knife is crucial in assessing how much force is needed to puncture the human frame, ‘the edges of the knife above the tip are of little importance in facilitating entry. Once the tip is through, the rest easily follows’, which means that the force needed is not necessarily tremendous if the tip is sharp: ‘the most important factor in penetration is the sharpness of the extreme tip of the blade. With a very sharp tip, a knife can be introduced up to the hilt by pressure of only one finger,’ writes Dr. Nolan. Which blows away all arguments sustaining that a woman is not capable to stab a man.

According to Dr. Nolan, it I very difficult to estimate the force necessarily for a particular stabbing because there are so many parameters in play, but the speed of approach has to be considered: ‘a rapid stab will penetrate the skin with minimal force whereas the same knife pressed slowly against the surface will require far more effort for penetration’. Another factor is the resistance exerted by the skin and clothing: ‘clothing does influence the penetration force of implements and always increases the force required’, but ‘thin cotton shirts and T-shirts do not add a substantial amount to the force required for penetration. We also have to know that the skin ‘is the most resistant tissue apart from bone or cartilage and once punctured, the knife will slide into the chest or abdomen without further force being required, as if penetrating the membrane of a drum. Thus a deep wound is not necessarily a ‘savage blow’ in the chest or abdomen.’ These studies show that when using a sharp-tip blade, the necessary force is far less greater than what people have suggested based on their own impressions, simply because the biomechanical of stabbing has not been studied enough.

Of course we don’t know much about the knife used in Elliott’s case, which was kept by the police, except that it was a tapered blade, a probably very important detail. Plus,  this sentence written by W T Schultz in ‘Torment Saint’ has always sent chills along my spine ‘A few nights prior she and Elliott had stayed up sharpening a new set of knives’ (page 318)… I never understood this sentence placed in the narration of the events of October 21st, I never understood why Schultz and Chiba found the need to tell us this, I never understood why Elliott and Chiba were sharpening knives in the middle of the night.

Last point, but not least, according to these studies cited above, ‘survival rate from stab wounds has increased dramatically, in recent years, owing to skilled and timely medical intervention. Stab wounds that previously were fatal, including some cases of stab wounds to the heart, can now be treated.’ As we all know, it was not the case for Elliott because he didn’t get this ‘timely medical intervention’, despite one person being present at the scene. This is completely unacceptable and this other aspect of the case has not been stressed enough.

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2 Responses to “What Do We Know About Forces Necessary To Stab Oneself?”

  1. michelle dickson

    This is just bizarre. While reading your article, I was shocked to read the similarities between Elliott Smith’s and my brother’s death. He too died by two very deep stab wounds to his chest, without hesitation wounds. The knife was a ceremonial dagger with approximately a 9 inch blade. It was purchased by he and his girlfriend, while visiting the middle east. His girlfriend was in the home when it happened. She called me before the paramedics, and claimed she couldn’t turn him over or check his pulse. Initially, she was investigated by police as a possible suspect. When questioned, she informed them, he had attempted suicide previously, and was using drugs. This was in fact, not true. There were no previous attempts of suicide, and at autopsy drugs were not found in his system. However, because of her claims, the coroner ruled his death of suicide.
    Eight years later, I am still feeling helpless, and heartbroken. I wanted to share my brother’s story, because as I mentioned, the similarities are astounding.

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