“A” is for Alibi was written by Sue Grafton in 1982. The novel is based on a murder case where the victim dies after taking medication that had the content of the tablet substituted to a toxic substance.
What makes the story even more interesting is that Sue was going through a divorce and many aspects of the plot were inspired on ways she’d fantasize killing her own husband.
Feeling like killing your partner? Next time try writing a novel about it. Seems like a good therapy and you might even be writing the next best-seller.