Crime shows make blood-spatter analysis look foolproof, as easy as seeing flecks of blood and knowing from which direction an assailant fired a gun. But the reality is far trickier, as new research inspired by the 2003 murder of actor Lana Clarkson shows. The late music producer Phil Spector was convicted of shooting Clarkson in the mouth at close range, though his lawyers argued he couldn't have pulled the trigger because his white jacket carried only 18 tiny drops of blood, per Science. This, they said, suggested Clarkson committed suicide in Spector's vicinity. This intrigued Alexander Yarin of the University of Illinois-Chicago, who tested the theory in a pair of studies published in Physics of Fluids. Together with colleagues from Iowa State University, he discovered that a shooter could kill a person at close range and, under the right conditions, avoid the blood.
This has to do with how "muzzle brakes" in a gun divert combustion gases. These gases escape "in a series of turbulent vortex rings" that can interfere with blood droplets sprayed in the shooter's direction, known as blood back spatter, per a release. "At shortrange shooting, the muzzle gasses interfere with the blood back spatter and deflect droplets," Yarin explains. In simulations and experiments using a foam container filled with pig's blood, researchers found the gases not only broke apart blood droplets into smaller droplets about a tenth of their original size, but also reversed the direction of the blood, forcing it back toward the victim, New Scientist reported in April. Blood even landed behind the target. This explains "how [Spector's] outfit could have been basically clean," says Yarin. And it's "essentially physically sound." (Read more forensics stories.)