Electron microscopy of the anthrax sent to media outlets and politicians in 2001 provided vital clues to how spores were prepared (Images: Sandia National Laboratory)

KEY forensic evidence in the US anthrax attacks of 2001 has been revealed. The FBI had previously prevented the scientists involved from speaking publicly about their findings in case this interfered with court proceedings, but last August, after chief suspect Bruce Ivins committed suicide, the case collapsed and the FBI lifted many of the restrictions. This week, some of the scientists involved revealed their results at a scientific meeting in Baltimore, Maryland.

These show how …