PANAMA CITY, Panama - These are the only two things known for certain about a wayward shipment of 3,000 AK-47 assault rifles that has created an uproar in at least three countries: (1) The shipment left Nicaragua on Nov. 2 aboard the 200-foot, Panama-flagged tramp steamer Otterloo. (2) It was bound for the Panamanian police. Everything else about the shipment remains a mystery. But the 173-ton arsenal, bought from the Nicaraguan police in a deal that seemed so clean Managua officials had notified the U.S. Embassy, evolved into one of the largest and most daring arms smuggling capers in the...