Reports of bullying are common -- with adults and children participating. Actions could be as simple as attempting to take away an assistive device or as brutal as murder. As this blog details, sometimes the murder is given sanction or even excused by society: http://genderbitch.tumblr.com/post/19204518306/another-murder-please-no
For a moment, look at it under the lens of "information flow." Within the social network, we have a node which is interdicted -- refused information and resources. Access to this node by outside units (someone investigating a complaint about harm to a disabled person) may be made even more difficult by gatekeepers who are conspiring to present a certain picture (generally the "noble suffering protector") to the investigators.
If this is a "given", then the question arises "should the disabled person have an information advocate who is not their caretaker?"
It's a good question. I'll think about it.
Talcott Parsons, "The Sick Role and the Role of the Physician Reconsidered." Millbank Memorial Fund Quarterly vol.53.no.3. Summer 1975. pp. 257–278.