Although the reliability of blood-spatter analysis was never proven or quantified, its steady admission by courts rarely wavered, even as the technique, along with other forensic sciences, began facing increasing scrutiny.

In 2009, a watershed report commissioned by the National Academy of Sciences cast doubt on the whole discipline, finding that “the uncertainties associated with bloodstain pattern analysis are enormous,” and that experts’ opinions were generally “more subjective than scientific.”

Still, judges continued allowing spatter experts to testify.

Subsequent research, funded by the Department of Justice, raised questions about experts’ methods and conclusions. But little changed.