The Critical Response Group
The FBI's Critical Incident Response Group is a special forces unit inside of their actual special forces unit. They show up during the worst part of the worst situations. You'll commonly see them roll up during hostage situations or active shooting incidents. These folks are extremely trained for any type of incident, so much so that they are commonly charged with training local police forces.
Tracking Crime
The FBI uses the Uniform Crime Reporting Program to track all serious crimes. These crimes include murder, rape, robbery, aggravated assault, burglary, larceny-theft, motor vehicle theft, and arson. The program has been in place since 1929. All statistics from this program are available to the public online, so you can see exactly what they've been up to.