Ironically I'm a commissioned Crime Scene Investigator for the Tulsa Police Department, and I instruct photography for the department. Where are you located? I'd be happy to help him out if you're close.
The quick and dirty way to shoot accidents is to get a tripod and use the non-flash auto settings, NOT THE GREEN BOX. Full auto wants to use flash, most accidents occur at night on poorly lit roads. He must have a tripod and patience.
Have him learn exposure and white balance. Don't trust the AWB at night as most lights are sodium vapor and all of his images will be yellow.
I would recommend RAW but it depends on his departments SOP / Policy.
Let me know if I can help. This is a great place for photo advice and I use it as a learning tool for my side photo business. However there is a huge difference in crime scene photography and non-crime scene photography. The principles of photography are the same, but the legal requirements and court admissibility are different.
FYI, for those who don't know. Many departments, even very large ones, offer very little training for photography. An unfortunate side effect is the overuse of the GREEN BOX. In my department we have 18 crime scene investigators and 17 of them use the green box, guess who doesn't.
It's fast and dirty and if you take enough poor quality pictures saturated with flash blowing out both ends of a histogram, you might get enough pictures for prosecution. This is not how I operate, but it is how many departments shoot crime scenes.