I've said this many times, you don't get a second chance to do it right the first time. Investigators have a tough enough job when investigating a death scene, so doing more is never popular. They must control the scene, prevent unauthorized access, avoid contamination, keep the bosses happy and create an investigative plan to capture the suspect.
This is partly for myself, so that I remember to read this article later, but also for other crime writing folks like myself. And as a side note, the author of the article, Joe Giacalone, offers himself out to authors as a resource on Google+. Happy writing.