FIRING bullets at blood-filled filter cartridges from a kidney dialysis machine might seem like mindless destruction, but it could give forensics investigators vital clues. The cartridges' microstructure seems to accurately reproduce the effects of shooting at real flesh, and one expert reckons this could help detectives model patterns of spilt blood at scenes of shootings.

Interpreting blood "spatter" at a crime scene is central to reconstructing what happened, but stand-ins for human flesh do not mimic the effects of shooting a real live body particularly well. To reproduce various spatter patterns, investigators normally soak a sponge in blood and shoot at it. But this is a poor model because the body doesn't contain many reservoirs of pooled blood. Unless a bullet hits an area such as an open wound or a main artery, then spatter will actually be minimal, says Peter De Forest, a forensics expert at John Jay College ...