A rookie police officer, with only weeks on the job, crossed paths with the would-be terrorist who is charged with plotting to bomb the Herald Square subway station. Beginning in November 2002, the undercover officer made visits to an Islamic bookstore in Bay Ridge, Brooklyn, and said he listened to the store clerk, Shahawar Matin Siraj, 23, predict further attacks on New York City, possibly on Wall Street. The officer, who testified yesterday at Mr. Siraj's trial in Brooklyn federal court under a pseudonym, Kamil Pasha, retold of conversations that suggest that Mr. Siraj drew satisfaction from tragedies ranging from...