Quick note to current would-be researchers: no, you cannot take home the heads of dead prisoners to your apartment and experiment on them. For one thing it’s just not hygienic. But of course so many other laws and ethical guidelines exist today that would rule out not only that, but most of what is described above to have taken place in the name of scientific research.
“Before the Anatomy Act of 1832, the only legal supply of corpses for anatomical purposes in the UK were those condemned to death and dissection by the courts. Those who were sentenced to dissection by the courts were often guilty of comparatively harsher crimes. Such sentences did not provide enough subjects for the medical schools and private anatomical schools (which did not require a licence before 1832). During the 18th century hundreds had been executed for trivial crimes, but by the 19th century only about 55 people were being sentenced to capital punishment each year. With the expansion of the medical schools, however, as many as 500 cadavers were needed annually” – read more on bodysnatching and grave robbing at https://en.wikipedia.org/wiki/Body_snatching .
In case you were wondering, “The Anatomy Act 1832 (2 & 3 Will. IV c.75) is an Act of Parliament of the United Kingdom that gave freer licence to doctors, teachers of anatomy and bona fide medical students to dissect donated bodies. It was enacted in response to public revulsion at the illegal trade in corpses” – again, read more about that at https://en.wikipedia.org/wiki/Anatomy_Act_1832 . And, note the use of the word ‘donated’. After 1832 it was only donated dead people that scientists were legally allowed to experiment on. Well, in the UK anyway.
Then again, confidentiality was totally blown!
PS: You can read lots more interesting accounts and reports of 19th century shenanigans in Christopher Edge’s book if you get hold of a copy. See e.g. https://www.amazon.co.uk/Rollercoasters-19th-Century-Non-Fiction-Christopher-Edge/dp/0198357400 for more details.