I work with local LEO (local and state) and it's a myriad of legalities to have a "civilians" working with LEO, Even on a non-criminal case they can change to criminal in the blink of an eye. Chain of Custody, Personal Safety, Insurance, Mental Health (you can't unsee some of these things), as well as Resource Management all come into play.
If you'd like me to break the above down I am more than willing to if that helps.
It's important to know that UAS for Public Safety is a far cry from the normal UAS flying we do. It's not about taking "eye pleasing pictures" but acqiring DATA and also knowing what you're looking for. You're NOT looking for a lost person in the middle of a field trying to flag you down... there is a LOT going into "Lost Person Searching".
Also, if you really WANT to TRY and help, the best route is to contact your local Sheriff's Office or county Emergency Services and ask if they have a genuine NEED for UAS operations. Those 2 usually work together for Search & Rescue.
Keep in mind, that in order to not "drain resources" you'll need some training in order to safely and EFFICIENTLY integrate into an existing SAR scene. NIMS training is an absolute MUST and most Dept have a set series that they require to be completed before you can be considered for introduction into the "fold".
It's a monetary drain because you buy everything YOURSELF and you have to be self-sufficient upon a call-out. I have the means to go anywhere, anytime, and be Self Sufficient for the first 24hrs. That's food, water, weather appropriate gear, sleeping, and POWER.
I want to stress, this can take a huge emotional toll on you as a person (and your family) if you're not prepared for what you "could" see on a scene.