NAWA, Afghanistan  On the day after he completed a one-year sentence at the Rikers Island jail, Osvaldo Hernandez walked into an Army recruiting office in Elmhurst, Queens. He was a felon with a plan to change his life.

It was late in 2003. Mr. Hernandez had been convicted of possessing an unregistered pistol the year before. The Army, struggling to meet its recruiting goals, granted him an enlistment waiver for the crime and soon swore him in.

Four years later, Mr. Hernandez, 25, is Specialist Hernandez, a paratrooper in the 82nd Airborne Division in Afghanistan.

His transformation from inmate to productive citizen would seem to be complete. His Army supervisors say he is reliable, honest and brave. Barring something unforeseen, he will be honorably discharged at the end of his 15-month combat tour this year and hopes to become a New York City police officer.