chucha - Zarigüeya orejiblanca - White-eared Opossum

From what I have read the species of opossums in Columbia are the Black-eared, or common, and the Andean white-eared. So this would be the same as your other spotting, D. pernigra. Check out the range maps for the whole genus http://en.wikipedia.org/wiki/Didelphis.

A sweetheart of a Possum - look at that tail (2nd picture)

It might be this: White-eared Opossum
Didelphis albiventris
http://www.projectnoah.org/spottings/104...