Do fingernail grow after you die?

They don't, that's just a myth. After you die, you start to dehydrate, which pulls the skin back away from the fingernails slightly. It looks like the nails are growing, because your nail actually extends back from the cuticle a bit. Between that and the fingertips shriveling, it looks like the nails grew. Same basic thing with hair- the skin on the scalp tightens, and it looks like the hair got longer slightly. But when you die, the cells that actually produce nails and hair die as well- they aren't making anything new. It's just a trick of the whole decomposition process.