June 15th 1995: O.J. Simpson tries on a new pair of gloves similar to those found at the crime scene of his wife’s murder. Despite compelling evidence, the actor was never convicted for Nicole’s murder. The iconic photograph above shows the dramatic demonstration that devastated the prosecution when the gloves appeared too tight for Simpson’s hands. His defense attorney simply said: “If it doesn’t fit, you must acquit.” - And this seemed to remarkably sway the jury into finding him innocent.

Bloodstain pattern analysis (BPA) is one of several forensic science specialities that can help determine what exactly came to pass on a scene of a violent crime. Technologies for it are evolving constantly, which leads to a higher degree of accuracy than in the past.

Eduard Piotrowski published a paper entitled “on the formation, form, direction, and spreading of blood stains resulting in blunt trauma at the head” in 1895. The various publications that followed did not lead to a systematic analysis the way we know today. Herbert Leon MacDonell advanced the research that eventually culminated in the 1971 publishing of “Flight Characterisics and Stain Patterns of Human Blood”. He went on to present the first formal training course for bloodstain pattern analysis.

Crime scene investigator Sherry Gutierrez put forth some general principles for the analysis of gunshot wounds in particular that roughly indicate what can be deduced from those. These are as follows:

  1. The amount of forward spatter (away from the shooter) is greater than the back spatter (towards the shooter).
  2. The velocity of the forward spatter is greater than the velocity of the back spatter.
  3. Both forward and back spatter have a lower velocity than the bullet. (The relationship of the velocities from high to low can therefore be visualised as bullet –> forward spatter –> back spatter.)
  4. Both forward and back spatter form a “cone” of mist. 
  5. The density of the fluid droplets from an impact to a fluid-containing structure decreases as the distance from the bullet impact increases.
  6. High velocity wounds to bone may cause bone to go both forward and backward alongside the spatter.
  7. The bullet exits in the direction opposite of the shooter.

Forward spatter usually travels farther than the back spatter in the same incident. It also holds a larger volume of blood that expresses as individual stains than the back spatter does. Targets may move with the direction of the projectile upon the moment of impact, so (for example) someone who was shot in the back may move forward. Similarly, if the target is located in a moving vehicle the wind and other circumstances may affect the forward and back spatter to a degree.

Bloodstain pattern analysis can also be made visual by documenting bloodstains at the scene of the crime and measuring the angles of impact that can lead every trajctory back to an ‘origin point’. Nowadays, computer programs are used to visualise these calculations further and create a 3D-model of the circumstances of the crime. An older method is called “stringing” and consists of attaching a coloured string to the point of impact and running it to the termination point (like the wall or floor). The convergences and crossing points of these strings can then be used for crime scene reconstructions.


Here’s A Little Inspiration

Monica has another career in case you didn’t know. The singer posted this picture of wearing scrub on instagram with this caption 

“I have other dreams and aspirations so I Pursue them when my babies are asleep & my musics done!! Moral of the story #WeCanIfWeBelieve never give up on your dreams #YOUCAN #BeenAtWorkSince7yesterday #ThankGODforMyMomAndPa #ScrubsAndAMandatoryThermal #DatHawkBITIN LOL⛄️❄️⛄️ #UKnowItsColdWhenIGetThisPale LOL”

People quickly assumed she is a nurse but later on she released a statement saying

“ I’m not studying to be a nurse. I have a great respect for nurses. Especially seeing first hand all that they do & how they selflessly give of themselves. It is mandatory that we wear scrubs in my field as well. I’ve always had an interest in forensics. In my field we focus on giving the family much needed answers and closure in the event that they lose a loved one. I enjoy helping families during one of the most difficult times in their life. Thanks for checking with me. My post was never intended to be misleading. It was meant to just be encouraging because some days it’s just not easy but it’s all possible if u stay encouraged & believe.”



How To Read A Stab Wound

Most emergency departments do not see much penetrating trauma. But it is helpful to be able to learn as much as possible from the appearance of these piercing injuries when you do see them. This post will describe the basics of reading stab wounds.

Important: This information will allow some basic interpretation of wounds. It will not qualify you as a forensics expert by any means. I do not recommend that you document any of this information in the medical record unless you have specific forensic training. You should only write things like “a wound was noted in the midepigastrium that is 2 cm in length.” Your note can and will be used in a court of law, and if you are wrong there can be significant consequences for the plaintiff or the defendant. This information is for your edification only.

1. What is the length of the wound? This does not necessarily correspond to the width of the blade. Skin stretches as it is cut, so the wound will usually retract to a length that is shorter than the full width of the blade.

2. Is the item sharp on one side or both? This can usually be determined by the appearance of the wound. A linear wound with two sharp ends is generally a two sided knife. A wound with one flat end and one sharp end is usually from a one-sided weapon. The picture below shows a knife wound with one sharp side.

3. Is there a hilt mark? This can usually be detected by looking for bruising around the wound. The picture below shows a knife wound with a hilt mark.

4. What is the angle? If both edges are symmetric, the knife went straight in. If one surface has a tangential appearance, then the knife was angled toward that side. You can approximate the direction of entry by looking at the tangential surface of the wound edge. In this example, the blade is angling upward toward the right.

5. How deep did it go? You have no way of knowing unless you have the blood stained blade in your possession. And yes, it is possible for the wound to go deeper than the length of the knife, since the abdominal wall or other soft tissues can be pushed inwards during the stab.


A short, informative video on what nails can say about your health. Also, Hank Green.