Boris Tarasov, employee of the Russian-American Company, was arrested in San Pedro, California in 1815. As a prisoner of some political value, in 1816 he was sent from Monterey to San Blas and then Tepic. He requested to stay in Mexico or else be sent to Europe (I bet he was from Siberia, though). In 1820 the Commandant of San Blas reported that Tarasov had fled to Panama.
The documents translated by Michael Mathes in The Russian-Mexican Frontier, which contain most of the above, and the other sources I have consulted reveal nothing more about Tarasov's journey. Did he make it back to Russia?