I've worked as a caregiver in long-term care facilities and I can't say the abuse was likely during a the full 10 year period, but my hunch is that it's likely someone from the NOC (night) shift. Usually from 10pm to 6am.

Not always, but some of the shadiest caregivers wound up on NOC and NOC folks generally work as a skeleton crew with as few as just 1-2 people in a decent-sized facility of around 30 residents.

A caregiver once confided in me that their medication aid (it was just the two of them) never said hardly a word to them during night shift and disappeared to a different wing of the facility for the entirety of their shift, every worknight for a year. Not saying that guy abused residents, just that in a setup like that, a person would have basically free reign to abuse residents.