In fact, I have written some short stories in the mystery and detective genres, some of which are published on this blog.
Many mystery writers write about murders. Whilst it's perfectly possible to write a good, workman like detective novel that does not include a murder, these can be a bit pedestrian. After all, Dame Agatha Christie wrote 66 detective novels and 14 short story collections, and I think it's fair to say that the vast majority of them, perhaps all, even, involved at least one murder, perhaps more in some of her novels.
In her novels and short stories hapless victims met their death in a wide variety of ways. Though poisoning does appear to have been her top choice.
Other of her victims were drowned, garrotted with the string of their own musical instrument, stabbings, bashings over the head, strangulation, shootings, heavy objects dropped from a height, for example.
However, all of the murders in the fictional works of Agatha Christie are well-researched and are all valid and "doable" for want of a better word.
In fact on several occasions murderers and attempted murderers have been found out because medical staff reading an Agatha Christie story or novel had realised the symptoms shown by a patient in their care were exactly those shown by a murder victim in an Agatha Christie story. Some murderers were also suspected of using some of her stories as an inspiration for their crimes.
This link takes one to an excellent thesis on Agatha Christie and her novels by Darina Slámová
https://is.muni.cz/th/q3enn/Murderers_and_Their_Methods_in_Agatha_Christie_s_Detective_Stories.docx
Agatha Christie's knowledge of poisons came from her studying and becoming qualified as an apothecary's assistant.
So all her murders (especially those involving drugs, poisons or medicines) were 100% accurate and fully accorded with scientific and medical knowledge.
However, some novelists have played fast and loose with the murders they describe in their novels and they created ridiculous and highly convoluted murder methods that were fantastical and, based on scientific principles, doomed to fail.
Examples that I can think of was a mad scientist who invented a specially designed gun that shoots specially designed projectiles fashioned of dry ice, thus leaving no clues as to what had actually shot the victims.
There was also a mad scientist who invented a special high pressure glass-lidded murder box that literally squashed people so effectively that their corpses were paper thin and left laying around the streets for some reason or another.
There seems to be a theme here of mad scientists designing mad murder methods for reasons that seem perfectly logical to themselves but nobody else, including the bewildered readers.
And there's also the short story when the wife of a police detective murders her abusive husband by smashing him over the head with a frozen leg of lamb and then cooks it and feeds it to his CID colleagues who are investigating his murder and thus they inadvertently devour the evidence!
(The rather dashing image used to illustrate this blog post is used courtesy of OpenClipart-Vectors and Pixabay)