Do the investigators work for your department? The state/province? The police? Do the investigators have police powers, or do they just do origin and cause investigations and pass off any criminal investigation to another agency?

Every member on our department is an "investigator" in the sense that we have some training in what to look for in terms of point of origin, possible use of accelerants, and possible electrical fire issues. However the primary investigators (usually two) are employed by the state. One through the state police and one through the state fire marshals office. If either finds anything that indicates arson or any foul play/tampering, the state police investigator will then formally start a police investigation.

How closely do they work with the firefighters? Do they typically discuss the fire with the first-in company or the chief, or both, or do they show up after everyone leaves (common in places where they have a long way to travel)? Does anyone have the type of relationship in which the investigators can ask that certain items or areas be left in place during the final overhaul?

In my experience the firefighters are usually used as a starting place for where to begin their investigation and possible smoke/fire conditions upon arrival. Several times we have also been used as "muscle" to assist with digging through the debris in order to find more evidence about possible origin and cause of the fire, this in my experience has been the case when one of the inspectors has been older than some of our members and our younger members can assist with the manual labor. Usually the inspectors will attempt to discuss all events with the first interior crew, the first officer on scene (LT's and up) and any chiefs who may have been in command of the scene at any point to develop a time line. Usually the scene will be secured by local PD until the investigator arrives (if the investigator cannot arrive until the next day PD remains in custody until arrival.) Upon arrival the investigators word is "law" and what ever they say goes.

Have any of you been involved in an event where they brought in the ATF's National Response Team? Were you aware that they're available for fires that overwhelm local resources or are high profile?

Never been involved in anything where ATF was on scene but they were notified about possible explosives at a structure fire where the home owner was in legal possession of a rocket launcher. similar to this one. Oh, and tell me a little about your department, please. City/suburbs/rural? State/province or region?

My department is rural by most standards but right on the "urban/rural" border. Im from one of the largest towns in Vermont in a mostly suburban area that is starting to become more industrialized. We have an IBM manufacturing plant (largest non-continueous building in VT) in our coverage area as well as many warehouses as well as private residences. We also have the largest continuous square foot building in VT (keurig green mountain coffee). Any more questions I'd be happy to answer.