Read Barbara Tuchman. She wrote the nobel prize winning history, The Guns of August, and was well known for her elegant style and eminent readability in addition to her piercing historical insights.

She wrote a series of essays on history and how she worked, which were gathered into a collection called Practicing History.

Both works, and many others by her, are available on Amazon.

If you're writing about a murder I'd suggest you also read, if you haven't yet, In Cold Blood, by Truman Capote. I understand that Capote has been accused of playing fast and loose with the truth in his book, but his writing is nothing short of delicious.

Capote comes at it as a journalist while Tuchman comes at it as a historian. Both are great writers with a lot to teach you.

Edit: Regarding footnotes, they aren't necessary, but you should replace them with endnotes. If you have no notes, how can people verify your claims? Endnotes take away the eyesores of large explanations and addendums scrawling up and down the page.

Am I crazy for not using footnotes?

The entire point of footnotes is that removing them should not affect the cohesiveness of a book. For me the hardest part of any written piece is deciding what information to not put in. I'm the author, of course I think it's all cool and deserves to be read. That's what footnotes are for.

What's not exactly clear from your question, though, is whether this is a historical fiction novel, or if this a book about a murder that actually took place.

Whether you use footnotes or endnotes or what have you, do yourself a favor and keep track of your sources and evidence from the beginning. You don't necessarily have to keep perfect citation style if you are not intending the notes to be used anything but internally, but you are going to have to keep track of these things if you are going to sell it as non-fiction, and to remember where you got some scrap of information later if someone asks you about it (including publishers, fact-checkers, the like). You will be doing future-you a favor. As for whether the final product will have notes, that is a decision between you and the publisher, and depends on audience and intent.

Check out Erik Larson, if you haven't already. Thunderstruck, Devil in the White City, or Isaac's storm. He does pretty enjoyable Pop History IMO, and his focus is very much on the approach you seem to be looking for - ie looking at a small subject and tying it into the larger events of the time. The biggest critiscism I hear, which is something I would say you want to aim to avoid if you are looking to be a "bridge", is that is can be hard to tell what is firmly grounded in his sources, and what he is extrapolating.