Good old Ninhydrin. The CSI shows love it, and all of the other alternative light source / chemical processing tools. They make for good drama. Processing them in Photoshop used to be a bit of a chore.
Now, there's several ways to get a good binary image. Now that we can use Adobe Camera Raw to develop JPEGs and TIFFs, we can use ACR to begin the work on chemically processed latents.
Here are some quick/dirty settings suggestions for ACR. Dump the Saturation all the way down and the Contrast all the way up. You can also pump up the Clarity slider as well. Blacks can be set from 20-50 depending on the strength of the chemical's signature in the image. In our case, I've chosen 40.
Once you move the image into Photoshop CS4 - load the Forensic Photoshop Configurator Panel and begin your work.
With the Forensic Photoshop Workflow applied, these prints now display their detail in stunning clarity - clarity that's essential for both the analysis and for courtroom presentation.