Its a "How-to" type of essay. Forget the name of it, however:

I'm writing about a murder, or that I'm explaining HOW to commit the perfect murder, but I'm stuck on starting it.

Any ideas?

not interested in becoming an accessory to your intentions

"perfect murder is a subject of many books, movies and thoughts.
Some of us might have dreamt about meeting someone like the killer from Hitchcock movie "Strangers on a train", but happily, those are just thoughts.