How to Tap a Computer

Besides following them, bugging them, wiretapping them and digging through their trash, the FBI got the goods on the alleged CIA mole and his wife by conducting "electronic surveillance of ((Rick)) Ames' personal computer," according to the affidavit. The FBI won't say exactly how it did this, but electronic experts have some intriguing ideas that illustrate the advanced state of computer snooping.

One way to look into a suspect's computer is remote surveillance. Parked just down the block, agents are able to pick up the electromagnetic waves that dance across a suspect's computer screen and convert them back into characters and words on a monitor. They can read everything the suspect is writing. While imaginative, this method is unpopular with law-enforcement authorities because they have to sit and watch the TV screen for weeks or review hours of videotape to see everything a suspect is doing.

FBI agents probably tapped into Ames' computer with a variation on old- fashioned bugging. One way would have been to enter his home and plant a device in the computer that would broadcast every keystroke. A more efficient method would have been to plant a bug enabling them to turn on the computer from another location, call up the internally stored files and transmit them by either radio or telephone modem to the FBI's waiting machines; the computer and modem would have been turned off by a remote signal. While in his house, the FBI might also have copied the diskettes he had on hand. And, surveillance experts say, they could have done all this without the suspect's ever knowing they had entered his computer.