11.   Ridge said the authorities had tracked the mail back as far the P Street Center.

12.   Since then, authorities have been tracking patients with encephalitis symptoms for West Nile infection.

13.   The authorities had been tracking Rocancourt for more than a decade.

14.   The authorities tracked Durst to Plano in late October, but he disappeared again just before they could apprehend him.

15.   The monetary authority tracks U.S. monetary policy to keep the Hong Kong dollar pegged to its American counterpart.

16.   This information gap makes it more difficult for authorities to track down the mail terrorists.

17.   Police and immigration authorities track down and deport them.

18.   Authorities tracked down the confidant, a former volunteer at a Manhattan home for women operated by nuns.

19.   Authorities tracked down the unidentified organization and found no record of the woman, and a forgery expert said Badri wrote the checks, the FBI said.

20.   Authorities were tracking them, the U.N. health agency said.