Financial abuse by my sibling of my parents belongings.

My parents recently moved to a care home and my sibling took responsibility to make decisions around my parents belongings and to take care of their finances. This is due to both parents having the early stages of dementia. For various reasons I started to have concerns when my parents belongings were disappearing from their former home, whilst my parents were in transition, until a firm decision had been made for them to remain in the care home. My sibling and I have had difficulties in the past around communication, I felt that because I am younger, he just didn't allow me to have a say, this led to a year of silence from my sibling by my siblings own request. My sibling recently re-opened communication prior to my parents entering the care home. My sibling asked if I wanted anything from my parents former home, I was surprised to be asked as they had not moved to the care home. I assumed he was talking about the kitchen equipment and some of the larger pieces of furniture. I told my sibling that I have no interest in their belongings. I informed the Social Worker about my concerns and she told me that she was not going to get involved, that I have to deal with my sibling directly. I have since learnt that it was her responsibility to intervene to safeguard my parents. My parents have now relinquished their former home, and their belongings should have been transferred. I visited my parents about 10 days ago, and to my horror there was no more items than I had seen on my previous visit. Having checked their closets, and room, they have the bare essentials, their clothing are old and tattered, and clothes, shoes, etc, that I remember them having at their former home, were not to be found! I approached my sibling and he said that is all that is left. Because of the difficulty around communication with my sibling, I didn't raise an issue until I could think clearly about this. This didn't sit well with me, I knew this was not the case that they had so little items. I have recently discovered items of my parents clothes, shoes, being sold on ebay, by one of my siblings children! I have spoken to various sources including an anonymous helpline service and I was told that this is theft, and that I should inform the police. I was also advised to raise a "safeguarding alert" with the social services for them to start an investigation, however, they would involve the police, even if I would prefer not to. This is a deplorable thing to have taken place and I am very angry with my sibling, however I would rather not get the police involved, as this is my sibling. This also raises concerns around my sibling having responsibility for my parents finances, given what I have discovered, I would prefer that I had that responsibility. I have thought of having an informal meeting with an Advocate present inviting my sibling and partner, to attend, to explain my concerns and try to sort this out amicably and to gain control of my parents finances. I have also been advised that I should be giving my parents total consideration to safeguard them and not to be so loyal to my sibling, as my sibling has acted in a dishonest way for financial gain. I am very distressed over this issue and, feel, for my parents, who are oblivious to what is happening. I would really appreciate anyone’s views on this. .