What is a 'murder book'

We were watching a crime show last night and in it they made reference to, and showed, a murder book. It was a folder about an inch thick.

This wasn’t the first show we’ve seen referring to this. But what exactly is a murder book? Wikipedia says:

But no mention of the size except for “housing the entire paper trail”, which makes me think it would not fit in a 1" binder.

So, is ‘murder book’ just the name for the boxes of files about an investigation or is there really a CliffsNotes version condensed down into a folder.

And if so, what’s its purpose?

I’d suggest Wikipedia pretty much summed it up. It’s documents relating to a case. One would suppose that a crime that took 2 days to investigate & make an arrest would have a ‘book’ that takes up considerably less space than a crime that took several years to solve.
It’s purpose is self evident; someone can refer to the documents for information with regards to the case. Files could be paper, electronic, photos . . .

The reason I’ve asked is, every time it’s represented in the movies or TV show (that I’ve seen anyway) it’s always represented as a small folder. Crimes in those shows are not solved in two days.

I would assume that a DA would need access to more than a Reader’s Digest version of the case files.

Are case files and a murder book the same thing or different things?

I have no background in law enforcement but I would guess that the vast majority of murders are actually pretty simple matters that don’t involve much complexity at all - where the circumstances and killer are obvious. Even 1 inch thick is still already quite a few pages.

Your Wiki quote says it’s the same thing:

I would guess that the concept of a ‘murder book’ as a thick binder with many pages is more in the realm of fiction-- the cold case that the detective couldn’t solve and still keeps them up at night, constantly adding to the book until they finally break the case.

I pulled a random Bosch novel, and the murder book was described as a “thick blue plastic binder with three inches of documents inside” on a cold case that Bosch’s mentor had been obsessed with for twenty years…

How big is a “patient medical file”? As big as it needs to be.

Which means that back in the pure paper era it was as many manila folders w metal prongs as needed. A 5" record set had 5 manila folders, a 1" record set had one, and a 12" set had 12. And only the most recent was pulled out and handled routinely. The others sat on a shelf in the back room and were only referred to when needed.

My take is cop shows show a notional idea of the latest freshest part of a complete murder book. Whether that folder is #1 of 1 or #12 of 12 so far is immaterial to the progress of the show. The working detectives are adding only to the latest one and if it ever gets to arrest & prosecution, the whole stack of separate folder(s) is given to the DA.

Nowadays it’s a disk folder on a document server.

My exposure to criminal cases is via criminal defense work, where I get access to the evidence in the case (called “discovery”).

It’s never been condensed down into any sort of book or folder. Anytime I’ve reviewed discovery it’s a collection of police reports and maybe pictures or recordings. I’ve never heard the term “murder book” used. The only thing added when there is a death is some sort of coroner’s report describing the condition of the body and the cause of death.

We used to have a file room in my old firm. The biggest cases were housed in banker’s boxes.

Yeah, nowadays we get a link to download the evidence (sometimes from www.evidence.com - seriously). My assistant puts it on Dropbox, which makes it very convenient to review on my phone, or to send to the client.