The U.S. government may now have the key witness who could tie Manuel Noriega directly to Colombia's Medellin drug cartel.

Under a sealed agreement approved by a federal judge in recent weeks at a closed hearing, Roberto Striedinger, a reputed pilot for cartel chief Pablo Escobar Gaviria, pleaded guilty to a drug offense.Investigators say that as Escobar's personal pilot, Striedinger would have had direct knowledge of the cartel's relationship with Noriega.

The former Panamanian dictator is charged with taking $4.6 million in bribes to protect the cartel's drug shipments through Panama to the United States.

Striedinger was arrested last year in his home on the Key Biscayne compound once used by Richard Nixon.