These are useful sites for crime scene photographers.

Crime-Scene-Investigator.Net
Iowa Division International Association for Identification

The International Crime Scene Investigators Association, created by Master Sergeant Hayden Baldwin, Illinois State Police retired, is an on-line forum allowing members to exchange information.  Got a question?  Post it on icsia.org.  More than likely someone will either have the answer or give you a steer in the right direction.  M/SGT Baldwin also runs a training and consulting service,  Forensic Enterprises, Inc.

The SWGIT/SWGDE site contains the photo-related guidelines published by the IAI's Scientific Work Groups.  As such, they are required reading for all police photographers.

You'll find crime scene processing checklists at many sites, including:

Hayden Baldwin's Forensic Enterprises, Inc.
NIJ Crime Scene Investigation Guidelines
NIJ Fire and Arson Scenes
NIJ Guide For Death Investigations

The following sites contain information of general interest.  You might have to dig to find articles of interest to photographers.

Onin.Com
Forensic-Evidence.Com
CLPEX.Com
Latent-Prints.Com
Zeno's Forensic Site
Reddy's Forensic Site
redwop.com/minutiae.asp
Crime and Clues