The Evergreen Woods facility in Brooksville, Fla., said the security guard charged with killing a resident passed a background check and drug tests, according to an article on the McKnights website.
Two residents were beaten with a car jack, and one — 83-year-old Joseph Giambrone — subsequently died of his injuries.
A weekend security guard, 22-year-old Brian Christopher Murphy, is believed to have beaten Giambrone and 88-year-old Miriam Lepp.
Investigators believe Murphy was living in his car and was on drugs at the time of the assault, Sheriff Al Nienhaus said he might have been looking for food.
Murphy had been hired four months before the attack.