[Lou Harpr]

Ngaio Marsh books take a long time to get to the murder but it never bothers me because I enjoy the writing, but contemporary custom is to introduce the murder early on. Maybe you could introduce another crime/mystery at the start to engage the readers and work your way up to the real case.

 

[Lou Harpr]

In Simon Brett's Charles Paris mysteries the amateur sleuth is a hard drinking actor, who keeps stumbling into murders. In Ngaio Marsh' books it's a police detective--most of the time. All cozies I can think of have a set of characters from the start, one dies, and another one is the murderer. The investigation is mostly about digging into the characters, as opposed to following police procedures.