Laws of Muktzeh on Shabbos
15. It is forbidden to handle a corpse on Shabbos. One may slip a pillow
out from under it so that it will not become foul-smelling, provided one
does not cause a limb to move in the process.
If [the corpse's] mouth is slipping open, one may tie the jaw so that it
will not open any further, but not in a way that will close the opening
that has already formed; doing so would be considered moving a limb (See
also Chapter 194, Law 12.)
Halacha-Yomi, Copyright (c) 2002 Project Genesis, Inc.