The Department of Health's most senior civil servant has said he was "shocked and appalled" by CCTV footage recorded at Muckamore Abbey Hospital.
Richard Pengelly was giving evidence to the Northern Ireland Affairs Committee on Wednesday.
It follows a report into the safety of vulnerable adults at the Antrim hospital.
It listed "catastrophic failings", and said staff had physically and mentally abused some patients.
A total of 19 members of staff are currently suspended.
At the meeting, Labour MP Kate Hoey said what had happened at Muckamore was "quite shocking" and asked if there was now a "grip on what's going on."
Mr Pengelly said while he was confident the working of the hospital had "fundamentally changed", he could not categorically state that he knew everything.
The CCTV evidence taken from the hospital was still being viewed, he said.
"I looked at some of the CCTV evidence and I was shocked and appalled in some cases by what I saw," he told the committee.
He said he met senior police officers on Friday to offer departmental support for their inquiry.
He also intends to meet the chief executives of Northern Ireland's five health trusts.
Mr Pengelly said he wanted to develop an action plan and aimed to "make good" on a commitment that no-one would call Muckamore Hospital their home, a year from now.
"We have people who have been there for far, far too long," he said.
The committee is examining health expenditure and policy.
On Wednesday, a fresh cancer strategy for Northern Ireland was also discussed.
Mr Pengelly said he would be publishing the terms of reference. He said the strategy was a "substantive piece of work which would take some time."
Committee chair Andrew Murrsion noted that Northern Ireland was "probably behind the curve" on bowel cancer screening.
Mr Pengelly said he had looked at this in some detail.
"The preparatory work is happening at the moment but I want to defer the actual decision making until we get a budget allocation for 2019/20."
On stroke services, Mr Jackie Johnston, deputy secretary of healthcare policy, told the Committee that the proposals for a public consultation would be out by March 2019.