[StrictDabbler]

A human or animal corpse that was accidentally mummified is still called a mummy. It's a technical term. A lot of mummies are just people who died in a peat bog, desert or ice cave.

Many mummies were also made cruelly rather than respectfully. The Maori mummified the fallen as trophies of war. The Inca would leave sacrifices to be mummified by the mountain ice.

So yes, somebody who dies in a derelict building and dries out is a mummy.