What can we do when we suspect financial elder abuse?

I asked a question about this a few days ago, and thank those that answered. I need to relate more specific information and re-ask, what can we do? I would like thank those who answered. But I think based on the answers I need to be more specific on the reasons we suspect elder abuse and what we have attempted to do about it. My sister the POA doesn't share any information about what is going on and get's angry when we ask, accusing me of trying to take over. When we were looking for nursing and assited living arrangements, my Sister ASKED me to find a place for them. We selected a good, save, clean place for them. They are not plush and fancy, but they are both comfortable, security is good and they are both very clean and run by a very reputable organization. Price wise it's about average. My sister had suggested a couple of other places, but they turned out to be very old converted apartment complexes which had next to no security and smelled terrible and were little more than warehouses for the poor. They were cheap to say the least. She is angry at us for suggesting the better ( and a bit more expensive) place. It was Mom and Dad's decision to select the one we suggested. My sister wants to rent Mom and Dad's house to 2 siblings. It is a 4 bedroom 3 bathroom home that would normally rent for about $1200 - $1400 per month in our city. My sister wants to rent it to them for $1000.00 per month as that's all they can afford with their combined incomes. Both of those siblings as well as my sister who is POA have had a lifetime of money problems. POA is behind on the Mortgage and has no savings, She and her husband have declared bankruptcy 3 times in the past. The other two siblings generally live month to month and have little or no savings. All three of them have made a habit of going to Mom and Dad (for decades) for money. My husband has had experience renting properties and helping a friend in renting his properties too. He's done the math, and tells me that after paying property taxes (which are some of the highest in the nation), insurance, upkeep and maintenance, repairing some of the things that my parents neglected, that there will be, at best, about $500.00 per month going to the care of my parents, which will cost in excess of $10,000 per month once Dad's Medicare benefits end in 2 months. We tried to explain this to my Sister (POA) but she just got angry because we were "taking good housing away from the other sister and brother". After this incident, both the POA and our brother have become increasingly rude and abusive to my husband and I. They have also made some thinly veiled threats to sue us. My came to Mom's house a few days ago when we were there and for no apparent reason blurted out to us that Dad was going gift him a valuable coin collection (The 1999 appraisal of the collection worth about $7,000.00). We know that dad gave him ONE of the coins for his birthday 2 years ago. My brother claims that Dad gifted him more the of collection recently. When we asked Dad about this, Dad said that was not true. We went to our Sister who is the Executor and POA about this, and she immediately told us that we had no right to ask Dad about it, and claimed that our brother had not said the things he did. That Dad had offered the coins, but he had turned him down. According to Dad, that's also a lie. Fortunately we know almost to the penny how much Mom and Dad have invested as of last month, but now the POA sister is working to exclude us from all financial information. We have talked to both parents about this, but like so many elderly parents, they can't believe their children could do this. Mother is old fashioned and believes that the Eldest child must be in charge even though that child has proven herself to be irresponsible with money. 6 months ago we arranged to have Mom and Dad's lawyer ( at their request ) to come to their home to have me added as co-poa and co-executor, but my brother apparently got to Mom ahead of time and talked her out if it. Nothing other changing the will and trust to reflect my married name was done. We know that at some point, if our brother and/or sister is careless enough to leave some proof of what they are doing, that we can report it to the government agency responsible for investigating Elder Abuse. We know we can also report to the police, but we also know that the police here consider this a civil matter and will rarely investigate, and then only in high profile cases. We also know that the State Agency is understaffed, underfunded by the state, and has come under fire for years for failing to investigate Elder Abuse. We're at a loss as to what to do next. How to go about finding evidence of wrong doing. Who to involve. Our problem is that while we have adequate income to live on (My husband is retired), but we're not wealthy enough to be able to afford a lawyer for a prolonged fight.