From the National Geographic:
"The underlying principles of the identification forensic sciences have never been rigorously scientifically proven," said Jay Siegel, director of the undergraduate forensic science program at Indiana-Purdue University in Indianapolis.
"This includes handwriting, fingerprints, and firearms, and tool marks," he said.
According to a new study, traditional forensic analysis often relies on untested assumptions and semi-informed guesswork. It can also sometimes produce the wrong results.
. . . . .
Little research has been conducted on the accuracy of traditional forensic sciences, such as the analysis of handwriting, firearm marks, fingerprints, hairs, and fibers.
"My guess is that the broader scientific community just assumed that the claims and assumptions of the traditional forensic sciences were rigorously tested at an earlier time," Koehler said.