A federal judge in Houston on Monday sentenced 65-year-old Douglas Crockwell Demmon of Galveston. Demmon in February pleaded guilty to distribution of child pornography.
The case was sparked by a 2010 tip from the National Center For Missing and Exploited Children originally investigated by Maryland State Police.
Law officers in Houston last year examined two computers in Demmon's home and recovered child pornography images.
Further details on where Demmon served as a U.S. park ranger were not immediately released.