Family members of the 81-year-old woman tell Eyewitness News the man committed the acts Monday around 6:45 p.m. in the woman's apartment in Pacoima, and the encounter was caught on video.
The woman's son-in-law says the video shows her letting the man into her apartment after he knocked, mentally unaware of what she was doing. After checking other rooms, he returned to the living room where the camera shows him sexually touching her and making her perform sexual acts upon him.
"The video catches him doing things that I wouldn't wish on anyone," said the son-in-law. "There's a lot of elderly people in the community. This guy needs to be off the streets. It's probably not the first time and it won't be the last time he's done this, or will do this."
LAPD officials said a suspect taken into custody Friday afternoon, adding that he was still in the area.
Anyone with information is urged to call Crime Stoppers at 1-800-222-TIPS (8477).