Bloodstains are really tough to eradicate. Tiny drops of spatter patiently wait on walls for luminol to uncover them. Blood seeps into carpet padding, behind baseboards, and inside of drains.

Now, forensic scientists in Australia show that even paint cannot hide bloodstains. Rachel Ehrenberg’s Science News article, “Camera Hack Can Spot Cleaned-up Crimes,” describes how infrared photography can reveal blood hidden under paint. Even six layers of black paint could not hide blood spatter. The article includes tips by a specialist in art conservation and imaging about the type of paint a murderer might use to cover a crime.