Some good info to add if the OP-er doesn't mind...........
But amid this growing concern over being buried prematurely, another worry began driving innovation: body snatchers. Sometimes known as "resurrectionists," corpse thieves would exhume and sell bodies to doctors, medical instructors and students for anatomical study.
https://99percentinvisible.org/article/grave-guns-coffin-torpedoes-vintage-defenses-aimed-foil-grave-robbers/