A Bronx nurse's aide is under arrest for allegedly abusing an Alzheimer's patient.

Diana Valeitin told NY1 she had concerns about how her grandmother Anna was being treated at the Gold Crest Care Center in Pelham Gardens.

She said she set up a hidden camera in the room, which allegedly caught Sandra Kerr, 55, snapping her grandmother's arm back, pushing her into the metal railing of her bed.

The Attorney General's office says that Kerr, a certified nurse's aide at the center, is under arrest.

"I was horrified," Valeitin says. "I couldn't believe it. I put the camera in thinking that something was going on, and when I actually saw it, I was horrified and heartbroken because she's just [defenseless]. It was just heartbreaking."

Kerr is charged with willful violation of the public health law and endangering the welfare of a physically disabled person.

She faces a year in jail if convicted.