Microbial forensics combines principles of public health epidemiology and law enforcement to identify patterns in a disease outbreak, determine which pathogen may be involved, and trace the organism to its source.

Since investigators must consider potential prosecution and presentation of evidence in court, biocrime investigations demand careful controls and standards for validation and evaluation of technologies and the data they produce. Scientists can easily evaluate new methods of detecting organisms implicated in a bioterrorist attack, but taking the resulting evidence into a court is another matter. Any microbial evidence, such as anthrax spores, that links to a suspect has to meet stern standards.

Here Comes the Nudge
We're not talking about a jury of your scientific peers, we're talking about lawyers, judges, juries, said Abigail Salyers, professor of microbiology at the University of Illinois and past president of the American Society of Microbiology. The consequences are not just having a paper rejected by a journal, but rather of sending someone to jail.

Salyers said even if the anthrax perpetrator was caught, it might not be as easy to achieve a conviction, especially if the spores are part of the physical evidence. If PCR based tests on the spores found in the suspect¹s possession were the same DNA signatures as the spores found in the letters, that¹s fine for scientists.

But if you took that into court, all sorts of questions arise: What does "same" mean? Does it have to be 100 percent identical? Even if it's 100 percent identical, does it really prove that it's the same? Salyers said.

Salyers sees two main problems. First, although the technology for doing DNA based and other molecular analyses is widely used and universally accepted in the research community, the kind of rigorous validation and development of appropriate quality control standards for the use of this technology in forensics is still not well developed.

Research is under way, but it might still be fairly easy for a defense lawyer to raise questions about accuracy and interpretation, much as happened in the infamous Simpson trial, she said.

This is not necessarily due to weaknesses in the technology but rather to the fact that scientists had not thought about forensic uses and thus had not developed the validation and quality control guidelines appropriate for legal application. This should not be a difficult goal to reach, however, because rigorous validation and quality control guidelines have been developed for the use of biological technologies in hospital laboratories.