Police suspect a former care worker at a nursing home in Gifu Prefecture, central Japan, of assaulting and severely injuring an elderly resident while on duty two years ago. They arrested 33-year-old Takeshi Odori on Sunday.
The woman in her 90s is one of two residents of the facility in Takayama City who were found severely injured over a two-week period in the summer of 2017. Three others were found dead.
He is suspected of assaulting the woman in August 2017, about one hour before she was found with broken ribs.
The suspect wrote on his blog and told NHK at the time that he had entered her room, but only to change her diapers.
Police say records kept at the facility and an analysis of surveillance footage suggest the assault took place then.
They are also looking into whether Odori was involved in the other incidents, because he attended to all five residents.