stakeout

stakeout
    n 1: surveillance of some place or some person by the police (as
         in anticipation of a crime)
    

21 Moby Thesaurus words for "stakeout":
      bugging, cloak-and-dagger work, counterespionage,
      counterintelligence, electronic surveillance, espial, espionage,
      following, intelligence, intelligence work, military intelligence,
      observation, secret police, secret service, shadowing, spying,
      surveillance, tailing, trailing, wiretap, wiretapping