Desper, though, beat the odds that are a ghetto child's grim destiny. Athletic ability and an enlistment officer saved him, Desper explained, and the Army happened to make him an M.P. So after his service hitch, he took the patrolman's exam in Montgomery County, just outside Philadelphia, where he had grown up.

By then, though, Desper was no longer a policeman, except in his heart of hearts. There, he said, he always will be, just as he always introduced himself on the witness stand: "Det. Desper, Badge No. 138."

"It's not a normal existence, but in a strange way it's addictive," Desper, 37, said, recalling the years when he led two lives. Desper lives with his wife, Anna, and their four children on a quiet street in a blue-collar section of Philadelphia. His own working day often started when his neighbors were sitting down at their dinner table, and lots of times he got home only as other families on the block were having breakfast.