Maggots and mugshots with PhotoFit noses, an old lady painted as she decomposes, pharmacy bottles in arsenic blue... these are a few of the gems up for view.

A Wellcome Collection exhibition launching in London in February and examining the history, science and art of forensic medicine will bring together all manner of macabre treasures, including artworks and artefacts dating back as far as the Middle Ages.

Among the displays are intricate 18th century Japanese watercolours capturing the decay of a dead noblewoman, and prototypical mugshots from forensic pioneer Alphonse Bertillon alongside their 1970s identikit progeny.

"Forensics: the anatomy of crime" will even include a literal murder scene: the floor tiles on which a friend of Mexican artist Teresa Margolles was killed.

But the most anticipated exhibits are likely to be a selection of never-before-seen case notes handwritten by notorious forensic pathologist Sir Bernard Spilsbury.

The yellowing index cards document some of the 20,000 autopsies Sir Spilsbury performed during his career, which spanned some of the most gripping whodunnits of the early 20th century.

His profile was such that the satirical journal Punch featured his portrait in a 1928 issue, on display in the Wellcome exhibition, declaring: "When arsenic has closed your eyes, this certain hope your corpse may rest in: Sir B will kindly analyse the contents of your large intestine."

"I get the impression that perhaps it became a default to go to Spilsbury rather than anyone else," Wellcome curator Lucy Shanahan said.

"Whilst Spilsbury's reputation did become damaged towards the end of his career, I don't think that necessarily means that he got everything wrong.

"I think he probably just got a little bit too caught up in his own ego and then perhaps wasn't doing as much of a thorough job as he should have been.

"Judging by his workload, he probably had far too many cases."

But many suspect that Sir Spilsbury made serious blunders during his career, including in what was arguably his best known case - the trial of Dr Hawley Crippen.

The American-born doctor was convicted at the Old Bailey in 1910 of poisoning his wife Cora following her disappearance, and Crippen's failed attempt to abscond with his mistress.

Investigators discovered human flesh in his cellar that Sir Spilsbury testified must have come from the missing Mrs Crippen, all but delivering Crippen to the gallows.

But nearly 100 years later, US scientists called the pathologist's findings into question, with DNA testing of a Spilsbury slide they said showed the flesh had belonged to a man.

Whether or not the gruesome find in Crippen's home did indeed belong to his late wife, Ms Shanahan - who has spent nearly three years poring over the documents in the forensics exhibition - does not believe an innocent man hanged.

"(Crippen) was definitely up to no good," she said.

"He had a mistress, he had a reason to leave the country, so it must have been fairly serious.

"There are a lot of question marks that are left hanging, but I'm sure he wasn't squeaky clean."

Though Spilsbury's notes on the Crippen case are not among the thousands owned by the Wellcome Collection, the forthcoming exhibition will feature press clippings and courtroom portraits from the trial.

The public will also get a rare glimpse at lesser-known cases pursued by Spilsbury, including that of young Helen Elphinston-Dalrymple, who died when she had dry shampoo applied at the Harrods hair salon in 1909.

Ms Shanahan said there may well be whispers, hidden in the trove of terse post-mortem examination notes, of innocent men sent to their deaths thanks to Spilsbury's testimony.

"It would be an interesting task for a present-day forensic pathologist to undertake if somebody had an interest in reassessing his work," she said.

"We worked quite closely with a coroner at the beginning of the exhibition as a consultant, and I took him to see the Spilsbury cards.

"He was absolutely bowled over.

"He'd read so much about them, heard so much about them in the field, but never actually seen them - so I'm sure there are a lot of people who would love to get their hands on them."

The exhibition will run from February 26 to June 21.