Casefic

...what should I read? Looking for casefics mostly, as viscerally horrifying as possible?

There are excellent Sherlock fics that focus on mysteries—Verity Burns' “The Green Mile” is among the best known and most successful case fics, incorporating as it does a compelling plot and extensive deduction scenes while also exploring the relationship between Sherlock and John.

The story is also a ‘casefic’, i.e. a story which revolves around the investigation of a crime: someone have been poisoning and killing alphas, and the resolution to the investigation turns out to have potentially groundbreaking consequences for Sherlock’s future, as well as for omegas in general.