http://en.wikipedia.org/wiki/Komodo_dragon

This should sort out the mystery.

Any monitor can lay motionless for hours if it senses danger. They also have a tendency to disappear into holes very quicly and again not appear for a while . No matter what size they are not the easiest of animals to find, we often have to look for a problem animal for relocation and it can take days or weeks to find, if you are lucky and in the meantime small livestock carry on disappearing In the bush we may see them and then they freeze solid when they sense us and dont move for a long time, some just run off quietly at high speed and after that you dont find them or see them even if you went looking for it and could track it, they do a proverbial disappearing trick. Thier camouflage is fantastic and makes it very difficult to see them in any forrested area which would mainly be shaded. We have a few small African rock monitors living around the house which steal chicken eggs, chickens etc but all we find is evidence of them and now and then tracks, sightings are very few, some of them are 2 to 3 foot long (nose to tail tip) and its amazing how they disappear. Before anyone asks, we generally leave them in peace as the livestock loss is not very large, although some can become a big problem.

A komodo dragon who is at the top of the food chain and has not yet learned to fear man (if it can) or anything else would be an easy catch. A komodo dragon is opportunistic and sees everything as food and with its poisonous bacterial bite (which most lizard type reptiles have) is scared of little if anything. They also do not have the tendency that other monitors have in disappearing down holes, in water etc.

Most probably a local species that has been sighted by someone who knows nothing about thier local fauna but watches a lot of wildlife programmes on tv.