Pat, this was one of the earliest symptoms my husband displayed. At the time, I could do no more than hide in the bathroom and secretly call the police for advice. Nothing ever came of it as the whole experience was just too new for me. But hubby was always a suspicious person, even before the dementia took over. It was a harrowing time for a while, but eventually passed.
You may feel you need to call several people: your GP; social worker and the police, at least to get advice as to how to progress and deal with incidents. I truly hope someone will step into the breach for you.