Final answer:
There is no exact statistic for the total number of operating crime labs available in the reference material. However, the involvement of approximately 17,000 law enforcement agencies in the FBI's UCR indicates a substantial number of crime labs that might be part of this network.
Step-by-step explanation:
Crime labs, which are fundamental in analyzing evidence and supporting law enforcement, are part of a vast criminal justice system in the United States.
While exact numbers can fluctuate, the presence of many federal, state, and local law enforcement agencies suggests a substantial network of labs.
A direct statistic for the total number of operating crime labs is not provided in the given reference material, but we can infer their importance and prevalence from the data on criminal justice employees and the FBI's data collection from roughly 17,000 law enforcement agencies.
The FBI's Uniform Crime Reports (UCR) involve the participation of these agencies, which likely includes various crime labs across the nation to process the collected evidence.