Week three of our course encompassed a presentation and hands-on workshops with the evidence response team and in real life it's nothing like the popular TV show CSI.

Better known as ERT, the 32-member team of the San Francisco division is staffed by volunteer agents. Nationwide, the FBI has 56 teams with about 1,200 members. When the team has a "callout", no less than 8 agents respond to the crime scene and their time on-scene can easily take an entire day. Their job description sounds easy; it's the collection and preservation of evidence. In actuality, the work is both meticulous and daunting.

After an initial presentation we broke into working groups and we each got a chance to try three key tasks: collecting fingerprints, using the alternate light source and learning the "art of the sketch".

As with all the evidence work, collecting fingerprints requires experience. The challenge of finding prints, dusting and collection were evident from our blackened fingers and work surfaces.

Next, we learned about the magical properties of light by using a device called the alternate light source (ALS). The ALS can emit a number of selectable wavelengths that causes resident materials to either absorb or reflect light. In one example, a carpet sample that contained an obvious bloodstain under white light later emanated a much larger stain by use of the ALS.

Finally, we learned the importance and art of "the sketch". The agent assigned to sketch duty is generally the first to walk a crime scene. Using landmarks, tape measures and laser sights, the sketcher produces a bird's eye view of the scene. It is their job to both accurately depict the scene where evidence is found and give the evidence gathering team directions at the scene.