What powers do elder abuse investigators have in regards to obtaining financial records?

As I've reported previously, my brother contacted Elder Abuse investigators and accused me of abusing my/our Mom (at least I have a VERY strong suspicion it was him since allegations of such are anonymous). Without repeating the details, the two investigators came unannounced, interviewed us separately and, after discussing their visit with my Mom afterward, we both felt that no other action would be necessary.... Mom is both physically and emotionally well (although she DOES have mild to moderate dementia and wants help paying the bills and I do the cooking for her). It's been more than a month and we still haven't heard back from them but now there's a very good chance that my brother has additionally charged that I am financially abusing her! Why? It comes from a phone call I made to him regarding the fact that Mom decided she no longer wanted the responsibility of paying her monthly bills. Since brother is a co-executor of her estate, I felt it was essential that I inform him of her decision and find out if he had any objection. Of course, he wanted to hear that from her so I gladly put her on the phone when, during the course of what should have been a short conversation, she declared that (in regard to her Home Depot balance), "... someone has used that card because I couldn't have charged that much." Suffice to say that it wasn't true and that she ALWAYS knew when that card was used and for what purpose (she even had a card sent to ME with MY name on it, for goodness sakes!). However, my brother went totally ballistic and thus began accusing me of taking financial advantage of Mom! Goodness, I have to sometimes BEG HER to let me pay for things sometimes and I DO contribute to the total home expenditures.

That being said (yes, I'm finally getting to the question part!... LOL!) and IF he's not only the source of the original elder abuse allegation but has now also relayed his suspicions/accusation of my having been/being financially abusive toward her, just how do they investigate such a claim? What power(s) do they have in regard to obtaining access to her and/or my financial records (checking accounts)? Does the bank need to notify us/me if someone/some agency is seeking access to our accounts? Mind you, I personally have absolutely nothing to hide and I am absolutely not taking financial advantage of my mother but I simply don't like the idea that ANY governmental agency could potentially delve into either one of our financial accounts without our knowledge! Anyone have any thoughts/answers to this type of situation? As before, and as always, I TRULY appreciate anything y'all have to add! Blessings!