Hundreds of times each year, teams from the Federal Bureau of Investigation slip into houses and office buildings. Armed with a judge's warrant, they seek information or plant bugs, and if all goes well, sneak away unnoticed. There are about 70 people on seven teams who work on such tactical operations, some of whom described their work to Ronald Kessler in The Secrets of the FBI. Some stay on the teams for their whole careers and have done as many as 5,000