I do not know Fred's sources regarding the Zacapa Department flag, but I have found some pictorial evidences of other flags of Zacapa Department. Of course, the main elements are a cactus and 10 stars, but there are various designs.
Based on pictures at these sites, the current version is a pale yellow (beige) flag with its arms in the center and name Zacapa is placed under the logo with black letters. Green cactus placed on a yellow disc but the stars are blue.
Images of current flag:
http://www.elzacapaneco.com/2011/05/leandro-morales-es-el-nuevo-gobernador-del-departamento-de-zacapa/
http://djduendezacapa.blogspot.com/2010/12/gobernador-departamental-desmiente.html
(Pictures taken in December 2010 and May 2011)
A previous flag could be white with a different type of its logo, consisted of cactus on a yellow disc, and ten white stars are placed around it on a light blue ring. Full name of department is placed over and under the logo.
Image of previous flag (picture taken on 29 August 2009): http://www.flickr.com/photos/luzyfer/3925293277/
I assume that Zacapa flag could change every time when a new governor was appointed.
Zoltan Horvath, 31 December 2011

Zacapa seems to have added a black bat face (?) to its flag - I wonder why? Nothing obvious on either the English or Spanish Wikipedia about that. I notice Wikipedia shows a flag with a white field, red disk and green stars (and no bat face).
Rob Raeside, 01 August 2014

Previous Flags

image by Fred Drews, 18 December 2011

image by Zoltan Horvath, 31 December 2011
Flag used in 2009

image by Zoltan Horvath, 31 December 2011

Coat of Arms

image by Fred Drews, 18 December 2011

Previously Reported Coat of Arms

image by Jaume Ollé