SINGAPORE, July 12 -- A hidden camera installed by a worried grandson exposed the repeated abuse of his 97-year-old grandfather by the family's Indonesian caregiver, leading to her 18-month jail sentence.

Siti Nurhayati Marwi Animan, 40, admitted to physically abusing the wheelchair-bound man, who had dementia and relied entirely on her for daily care, after video recordings captured her repeatedly hitting, poking and assaulting him over several days in October last year, Singapore-based news outlet CNA reported.

"There were bruises weeks before the incident, which prompted the installation of the camera," District Judge Arvindren R. was quoted as saying during sentencing last Friday.

The footage showed Siti striking the man on his hea...