Viktor Bout, a former Soviet Air Force officer who became known as the “Merchant of Death” for running what American officials have described as an international arms-trafficking network, was found guilty on Wednesday of conspiring to sell antiaircraft missiles and other weapons to men he believed were Colombian terrorists intent on killing Americans.

The verdict, in Federal District Court in Manhattan, was a rather prosaic end to nearly two decades spent in the margins of international terrorism and espionage. Mr. Bout has been accused of furnishing weapons to Al Qaeda and the Taliban and into civil wars in Africa, and was reputed to have a grasp on present-day Russian intelligence. His legend inspired the 2005 film “Lord of War,” starring Nicolas Cage.

Even Mr. Bout’s arrest and extradition were theatrical: he was taken into custody in Bangkok in March 2008 after being ensnared in a foreign sting operation run by the Drug Enforcement Administration; his extradition to the United States, which Russian officials strenuously opposed, took more than two and a half years.

But the trial, presided over by Judge Shira A. Scheindlin, took only three weeks, nearly all of it spent by the prosecutors’ making their case. Mr. Bout’s lawyer did not present any witnesses; the jury took less than two days to find Mr. Bout guilty of all four charges.