Actress Viola Davis has opened up about her sister's childhood sexual assault, insisting she's still struggling with the fact she has not been able to help her.

The How To Get Away with Murder star's sister was assaulted by a man when she was just eight years old. The ordeal has led to a life of substance abuse and homelessness and, as much as the Emmy Award winner has tried to help her sibling, she has not been able to.

"I have a sister, who, when she was eight years old, put on some roller skates with her friend, went down to the corner store... and was sexually assaulted...," Viola revealed at a benefit for the Stuart House charity. "She came home and she told my mom. My mom ran down to the store, started screaming at the store owners and they said, 'Leave that man alone. He does that to all the little girls!'

"My mom proceeded to flag down a police officer. They found the man. They put him in the car. I saw my little sister crying. My mom was crying, too and that was it."

Davis recalled watching her happy sister turn into an angry drug addict by the time she was 20, and she has been grappling with her issues ever since.

"A precocious, very intelligent, very creative child grew up to be frail, angry, a drug addict by the time she was 20," she continued... You pray that she finds peace and love and happiness, she gets off drugs. And then of course you open your eyes, and you're like, 'She's still on the streets...'

"I wish I could tell my sister that she's not dirty, and that she should not feel any shame for something that she literally was not responsible for. I wish I could save her life."