These machines can generally be calibrated to detect minute amounts or can be set with a higher threshold. The computer-driven analyzer uses chromatography to determine the nature of the sample. In about 4 seconds, it automatically checks for all types of drugs. When a drug or explosive is detected, a red light goes on and an alarm sounds. Each machine costs $60-70,000. The machines can be used as screening devices in security systems, as pre-screening devices in the field, and for conducting preliminary screening of evidence that will be further screened using chemical techniques. Although the machine's findings have not yet been used as evidence in court, they easily could be and probably will be. The equipment will not replace dogs, which are better for fast sampling of large areas. However, the machine potentially has a longer life span than a dog, will cost less per year, and requires no judgmental input from the operator. Although the machines are relatively untested, personnel from both the industry and the FBI predict that they will bring a new level of investigatory and laboratory freedom to law enforcement. Photographs