A Mystery Man Who Keeps the FBI Up at Night Officials hunting virtually full time for a Florida computer technician see him as the ultimate 'sleeper agent' in the post-9/11 world. By Josh Meyer Times Staff Writer September 3, 2006 CHARLIEVILLE, Trinidad and Tobago — Five years ago, as 19 Al Qaeda operatives in the United States put the finishing touches on what would become the Sept. 11 attacks, a frail, asthmatic computer engineer from South Florida paid a visit to this tiny Muslim enclave where he'd lived as a boy. Adnan Gulshair Muhammad el Shukrijumah, then 25, kept a...