1.   Undercover agents have been tracking him for weeks.

2.   A computerized fingerprint identification system, IDENT allows agents to track how many other times the detainee tried previous illegal crossings.

3.   According to the Russian account, Russian counterintelligence agents tracked Ms. Leberknight as she prepared to meet a Russian contact.

4.   Agents also tracked paint fragments from the exploded truck, which were traced for chemical content.

5.   Agents were tracking Cunanan in May while he was driving a car stolen from Chicago developer Lee Miglin, another man police believe was killed by Cunanan.

6.   Customs agents had tracked a large illegal shipment of Cuban cigars to a house in Connecticut.

7.   Customs agents tracked down the Hardys by mail, Mrs. Hardy said, suspicious that they might be opening a lighting store.

8.   Customs agents tracked him to a Mazatlan prison, where he was being held under the alias of Mariano Villegas-Zamora.

9.   Last month, the agents tracked cartel couriers carrying cash over the border from California.

10.   Law enforcement agents tracked down and arrested both McVeigh and Terry Nichols, precluding any private citizen from claiming the reward.