Bloodstain pattern analysts use their knowledge of blood spatter to figure out how a crime occurred.

Bloodstain pattern analysts, or blood spatter analysts, are specialists who gather information about how a crime occurred by inspecting the blood at the crime scene. By looking at the shape or path of it, a blood spatter expert can map the trajectory of a projectile or determine if a bloodstain was recently removed.

A fatal gunshot wound leaves a very different mess than a body dismembered with a machete. Each action has characteristics unique to it that result in what is called a bloodstain pattern. By (you guessed it!) analyzing this, a trained eye can tell what kind of weapon was used to inflict how many blows, as well as any movement that may have occurred during the attack and where both parties ended up. The oxidation of the blood can reveal how long ago it was spilled, which is essential for determining a window for when the crime occurred.

Any crime scene that involves blood (and given the nature of most violent crimes, the majority of them do) will call in a blood spatter expert to check it out. Whether the blood at the scene consists of a smudge, a handprint, a puddle, or a spray, an expert will take a good look and classify it as a passive stain, a transfer stain, or an impact stain. Large drops and pools are passive stains, which means they formed due to gravity rather than any particular movement. Transfer stains occur when something makes contact with blood, leaving a smear distinct from the source. Impact stains are caused by blood traveling through the air due to sudden contact with an external force such as a weapon. This is the sort of information any blood spatter analyst will use on the job.

Bloodstain pattern analyst work may include...

  • Identifying characteristics of bloodstains
  • Collecting blood samples from crime scenes
  • Determining when occurred
  • Interpreting lab data
  • Writing lab reports
  • Compiling scientific evidence for legal or investigative use
  • Testifying in court

Blood spatter analysts are typically employed by city or county law enforcement. This is one of those forensics jobs that requires both being present at gory crime scenes and clocking long hours in the lab. It helps to be able to focus on details that others could easily miss and to be able to interpret them using specialized equipment and knowledge. Crime doesn't keep to business hours, so flexibility is key; most members of a CSI team are expected to be on call and work some irregular hours. Blood is considered biohazardous, so there are strict safety protocols in place for interacting with it, from gloves to vials to full on hazmat suits. All of this is essential, but the most important skill for an aspiring bloodstain pattern analyst to develop is advanced pattern recognition.

It also can't hurt to have a background in chemistry or human anatomy, and most blood pattern analysts will need a Bachelor's degree in some sort of organic lab science as well as some forensics training and physics. You'll need to know everything there is to know about blood, specifically - both its visual characteristics and its scientific properties. It's possible to enter this field with an Associate's degree, provided a candidate also has relevant experience. In fact, regardless of academic credentials, an aspiring analyst will need to undergo a couple years of supervised training before they can work on their own. There are field specific workshops, seminars, and certificate programs available that can provide some of this training, and they can help you get to a fascinating career filled with blood.

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