On biological detergent breaking down organic material
In the household, hair and fat residues in the pipes are typically dissolved using strongly alkaine drain cleaners.

In addition to the hints and directions given in the commentaries, namely this and that you might want to consider, at least in part and for the dramatic effect, a biological solution:

In the preparation of skeletons for museum displays, adult insects and larvae of the bacon beetle (Dermestes lardarius) are frequently used. After gutting the carcass (I'll leave the gory details to the novellist), plan a couple of weeks for them.