Drugs bust search

[rag95.livejournal.com]

I think it's on AO3. It's a gen/friendship story. Lestrade and company are doing a drugs search of the flat, that leads to a revelation about John. He's a vampire but not one who drinks blood (don't want to reveal what he needs to survive for spoiler reasons). Does this ring any bells?

FOUND! "A Study in Observation" by Jupiter Ash