Power
The fire investigator is a hybrid profession, like a chimera or the dreaded Jackalope. You're part firefighter, part law enforcement, part scientist, and just a dash of fortune teller—to keep things interesting. All of that makes you a figure of authority to the general public, and even your average firemen and women will defer to your vast knowledge, wisdom, and insight. They may seem like Jedi warriors, but that just makes you their Yoda.
Your job starts the minute the fire goes out. Showing up at the scene of the fire, you'll quickly be ushered in under the crime scene tape. Once there, everyone will leave you to your work as you analyze the scene, take samples, photograph, and generally walk around like you own the place.
Next, you'll have to interview witnesses, from the loud mouths who embellish details to the introverts who just want to stay out of it. You need all the helpful information, so put on your best Detective Benson, knock on those doors, and collect those statements.
In the course of duty, you'll be called to testify in court about your findings and your evidence, and you can bet your badge that you'll have to back it up on cross-examination.
Finally, although you probably won't find yourself doing it all that often, you'll have the power to both carry a firearm and make arrests. That's quite a lot of power when you think about it. The only things Stephen Bull McCaffrey ever detained were the hearts of America.