Headlines involving abuse in care homes normally centre on allegations against staff, but is aggression among residents being overlooked? With homes increasingly taking care of those with more complex needs such as dementia and other mental health disorders, are staff able to cope with some who have challenging behaviour? File on 4 has found evidence that some residents are suffering serious assaults by others living in the same home. Some have died from their injuries. Allan Urry investigates the unsolved killing of one dementia patient. Are workers skilled enough to recognise and deal with aggression, before it becomes violent, and should the NHS and local authorities be doing more to support them? When the perpetrators themselves often have little understanding of what they have done due to the nature of their illness-are they also being let down? The programme reveals failures in the system that could have cost lives. Reporter: Allan Urry Producer: Emma Forde Editor: Gail Champion.