Douglas, ArizonaLEE MORGAN'S SMALL, spare office has the somber feel of a personal shrine. A Vietnam veteran with 30 years' experience in the immigration and customs services, Morgan does undercover and investigative work on the Arizona border, now the gateway of choice for illegal immigrants entering the United States from the south. Everything in his lair in the dusty frontier town of Douglas speaks to his patriotism and dedication: his Bronze Star, his Purple Heart, the three folded American flags--comrades' commemorative flags--and proud photos of his fondest undercover busts. Like everyone who works on the border, he has had a...