When Sgt. Beverly Zaporozan, an RCMP bloodstain pattern analyst (BPA), describes her favourite bloodstain — an impact pattern — as beautiful, her peers in the room start laughing.
"I know it sounds funny to describe blood as beautiful, but when you walk into a crime scene and you see this really nice V-shaped pattern on the wall, it is beautiful because it's textbook," says Zaporozan.
From the almost perfectly circular stains, to the elliptical stains that speak to the direction the blood travelled, to the blood that flows down the wall — these are clues that an analyst can use to determine the what, where, when and how of a violent crime scene.
"It's problem solving," says Zaporozan. "The blood is telling a story and you're interpreting that story that you'll ultimately report back to the courts."
All RCMP BPAs are first introduced to the subject with a basic bloodstain pattern recognition course that they take during their forensic identification apprenticeship.
From there, they can further specialize in bloodstain pattern analysis. As part of the training program to become an analyst, all Canadian BPAs are required to take a specialized math and physics course.
"While they learn pattern recognition and terminology in the basic course, this course helps them to understand how the patterns are created and how the blood acts in flight," says S/Sgt. Erin Pepper, the RCMP's forensic identification and BPA training program manager.
Understanding the science
In the course, BPAs learn to determine the area of origin of an impact pattern, in other words, where in a three-dimensional space the victim was when they were injured. One way to do this is called stringing.
This method determines the angle of impact and directionality using several spatter stains and strings to make a visual representation of the flight paths of the drops of blood that created those stains. Where they converge is the approximate area of origin.
When the RCMP was starting to use bloodstain pattern analysis in the mid-1980s, BPAs were using this method but didn't understand the scientific theory behind it.
They approached professors from the math and physics departments at Carleton University for answers.
"The instructors started teaching people this whole idea how a drop of blood, just like a bullet or a baseball, flies through the air in a curved trajectory and why, if you're early on in the trajectory, it looks like a straight line," says Brian Yamashita, an RCMP research scientist who works with forensic identification members.
Originally, it was a two-week course that was heavy in theory. Then when Yamashita took over teaching part of the course, it was shortened to one week and included more practical knowledge geared to police officers who don't necessarily have a background in science.
The confidence to testify
Course participants learn about quadratic equations, parabolic arcs and one- and two-dimensional motion, but they also learn other analytical techniques, like how to use a computer program to determine the area of origin, instead of using strings.
At the end of the course, participants apply that knowledge by analyzing an impact pattern in a mock crime scene.
"It gives them confidence to know there's a scientific basis in what they're doing," says Yamashita.
That confidence helps them when they testify in court.
Zaporozan has testified at many trials, including the trial of one of Canada's youngest serial killers, Cody Legebokoff. Zaporozan was involved in the second search of his residence where DNA of two missing women was found.
"There were low-lying spatter stains and indications of clean up," says Zaporozan. "My partner and I were able to speak to where the spatter stains were, what may have caused them, as well as how saturation stains that we observed were created."
Understanding the math and science and using that knowledge allows BPAs to be better able to defend their opinions and conclusions in court.
"Gone are the days of saying, 'Because I said so makes it so,' " says Zaporozan. "The math and physics course gives us the tools to better explain the math and science behind the analysis. And if I'm going to court and presenting a conclusion, I had better be able to back it up. If I can't scientifically back up my conclusion, I have no right making that conclusion."