in search of a climax without cliche

In the mystery I'm working on, in that there is a murder, and there will probably later be another apparent murder attempt, but there are really no bad guys. The second near-death would actually turn out to be a suicide attempt by the person responsible for the first death, once he's feeling both guilty and likely to get caught.

I'm not so much worried about the reader feeling cheated that there was no evil murderer. As I see it, the book I'm writing is promising a mystery surrounding a violent death and eventually a solution to what really happened and why, hopefully with some interesting character interactions along the way as well as the puzzle.

What I am worried about is how to structure a climax without the usual cliches of evil murderer trying to protect his/her position by threatening the main character. I don't want to resort to the cozy cliche of gathering all the suspects in a room for the main character to explain and accuse either. I have some ideas of things that should happen at the end, but not a climactic scene.

The main character is an amateur sleuth. Well, she never did that kind of thing before, but the events of this week inspire her to seek answers.

She may or may not interact much with the police. At least at the beginning she'll give them information that will narrow their investigation, but they would probably mostly be focusing on the forensics, and she'll be able to focus more on the interactions between the various characters, some seemingly insignificant little clues that she is able to put together in ways that the police wouldn't to point to a motive and an opportunity (i.e., breaking an apparent alibi).

She'll also discover some other interesting facts about her coworkers that might seem to point to reasons for others to have committed the murder but ultimately turn out to be unrelated.

She could figure out whodunit when and why before he attempts suicide and either realize that that is a risk and rush to prevent it or just happen on him immediately before, during, or immediately after the attempt. That would give more urgency to confronting the murderer, but it would rely too much on coincidence.

Or the suicide attempt could occur before she puts all the pieces together. It would look like an attempt at a second murder, which would mean looking in a different direction for the murderer and would appear to raise the stakes with the belief that there's someone going around making attempts on the lives of more than one person. But when the heroine figures out the events and motives surrounding the first death, then she'll also figure out that the same guy was also responsible for the second attack, that it was supposed to be suicide. And she could go confront him in the hospital. But that might be too anticlimactic.

That's what I was thinking. But then I'm still missing a climax for Act III.