A man accused of brutally murdering an aged-care worker and dumping her body in a Windale park has raised a defence of substantial impairment, claiming he couldn’t control himself at the time of the woman’s death. There is no dispute that Graham Anthony George Sloane, now 68, was the man who took Renee Mitchell, 38, from her kitchen while she was cooking dinner for her family on November 11, 2014, Newcastle Supreme Court has heard. There is also no question that Mr Sloane took Ms Mitchell to nearby Bangalay Reserve and stabbed her four times in the chest and once in the neck. And it’s not disputed that those injuries caused her death and that Mr Sloane intended to kill Ms Mitchell. But what a jury will be asked to decide is whether Mr Sloane was suffering from an “abnormality of the mind” at the time of the killing, meaning his capacity to understand events, judge right from wrong or control himself was substantially impaired by mental illness.