Minnesota's top forensic scientists study blood spatter

8:49 AM, Aug 16, 2013   |    comments
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ST. PAUL, Minn. - It is "Forensic Science Week" across the country. Governor Dayton has also declared it "Forensic Science Week" in Minnesota, highlighting the work of the state's top crime detectives. The idea is to raise awareness about what forensic scientists do and how Minnesota's forensic scientists are on the leading edge of this type of science, setting standards around the world.

We know that DNA evidence has changed criminal investigations, led to arrests, convictions, exonerations. The same is true for another type of forensic science. We got a unique look inside the state's top crime lab where forensic scientists are doing ground breaking research in the area of blood stain analysis.

The forensic scientists at the Minnesota Bureau of Criminal Apprehension have done one of the most extensive studies ever of blood evidence, specifically blood stain analysis. They have conducted countless experiments using slow motion video to observe and analyze how blood behaves under various circumstances.

The experiments were conducted using real human blood that was donated to the BCA for purposes of scientific research.

"Examining the size, shape and distribution of blood stains at a crime scene or on different pieces of evidence and trying to determine what mechanisms may have occurred that got the blood to that location," says Steven Swenson about blood stain analysis. He is a BCA forensic scientist who is an expert in the analysis of blood stain and spatter patterns.

While Swenson's work is not likely a topic you'd discuss over dinner, for the forensic scientists at the BCA and the law enforcement agencies and families they serve, being able to understand the compelling story blood tells at a crime scene means answers for loved ones and freedom or exoneration for the accused.

"We are really trying to understand the story and figure out how we can best solve the puzzle," says Swenson.

The videos were filmed at a speed of 10,000 frames per second providing extremely detailed images of what blood does when it hits a surface or something hits it. BCA forensic scientist Terry Laber showed us slow motion video of a muzzleloader firing. You can see the gases that come from the gun barrel. Those gases will push blood away, rather than sucking it into the barrel of the gun..

"It explains why we do not see blood on the weapon or the shooter in a lot of the shooting cases that we do," says Laber.

Where the blood lands and how it lands can show direction, distance, type of weapon and may ultimately determine the killer. Blood patterns created in the lab are patterns these scientists often see at crime scenes.

"We really want to identify what the evidence is saying to us," says Swenson.

Every year the BCA investigates ten to fifteen cases where blood patterns or spatter have become key evidence. Swenson recently testified in a Blue Earth County murder case where the suspect used a hammer as a weapon. He also analyzed evidence in a trial earlier this year where a jury found a man guilty of stabbing an Oakdale nanny.

Swenson says he is always affected by the humanity of what he sees at crime scenes. He hopes his work in the area of blood stain evidence helps more families find the answers they're looking for about what happened to their murdered loved ones.

"That part is interesting. It shows how fragile life is and that's definitely something that we see a lot of," says Swenson. "You don't take for granted those small things in life."


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