CCTV footage has revealed 1,500 crimes on one ward of Muckamore Abbey Hospital in County Antrim, the police officer leading the investigation has said.
The incidents happened in the psychiatric intensive care unit over the course of six months in 2017-18.
Police are investigating allegations about the physical and mental abuse of patients.
The hospital provides treatment for people with severe learning disabilities and mental health needs.
Twenty staff, mainly nurses, have been suspended at the hospital since 2017.
Allegations of ill treatment began to surface at Muckamore in November 2017 when it was revealed four staff members had been suspended.
In August 2018, BBC News NI reported there had been 53 assaults on patients by staff reported at the hospital – five of those incidents were investigated and substantiated.