Horrific moment pervert gets into 81 year-old dementia sufferer's apartment and kisses her before sexually assaulting her near her walker

A man sexually assaulted an elderly Alzheimer's patient after knocking on her door and taking advantage of her confusion.

No one would even have known about the ghastly abuse he subjected her to if her family hadn't installed hidden cameras in her home in Pacoima, Los Angeles.

The 81-year-old woman let the portly, bearded man in about 6.45pm on Monday, carrying a backpack that he put down next to her walker.

She slowly shuffled across the room, her condition leading her to believe she recognized him and was comfortable with him being there.

A man sexually assaulted an elderly Alzheimer's patient after knocking on her door and taking advantage of her confusion

The man embraced her, grabbing her back and leaning his face close to hers - unaware that police would soon see all the disturbing footage.

Police called what he did afterwards attempted rape and launched a manhunt that eventually tracked him down on Friday in the same area.

He is accused of forcing her to perform sexual acts on him and is expected to be charged with sexual assault.

'The video catches him doing things that I wouldn't wish on anyone,' her son-in-law told Fox 11.

'He knocked on the door. She's 81 years old. She opened the door and he let himself in. He starts looking around to make sure there's nobody in the house. He starts hugging her and starts to try to make out with her.

'She's not really fighting it off because, 81-year-old Alzheimer's patients, what can they do?'

The man embraced her, grabbing her back and leaning his face close to hers - unaware that police would soon see all the disturbing footage

The 81-year-old woman let the portly, bearded man in about 6.45pm on Monday, carrying a backpack that he put down next to her walker

The son-in-law said she didn't remember the abuse due to her condition, and they wouldn't have known if it wasn't for the hidden cameras.

The camera system, which they kept hidden to avoid her turning it off after forgetting what it was for, has alerts set up that told her daughter she was up earlier than usual.

She played back the tape and was horrified by what she saw. 

'There's a lot of elderly people in the community. This guy needs to be off the streets,' the son-in-law said.

'It's probably not the first time and it won't be the last time he's done this, or will do this.'