Angel Resendiz aka "The Railway Killer", "The Railroad Killer" was a serial killer suspected of 23 murders in the United States and Mexico.  On June 21, 1999 Resendiz was added to the FBI's Top 10 Most Wanted List.  Resendiz was executed via lethal injection by the state of Texas on June 27, 2006. 

Envelope mailed to his family in Mexico from what looks like the President of Mexico.