A defense attorney says police found no DNA evidence linking a 20-year-old woman to the kitchen knife that was used to stab her grandmother 20 times.

But a prosecutor says Hestina Harris' arms and clothing were spattered with Lillie Morris' blood after a 2014 attack at the rural Frederick County home they shared.

Lawyers gave their opening statements Tuesday in Harris' first-degree murder trial in Frederick.

Harris told police she saw a man in a ski mask running from the house near Burkittsville after the attack. She told investigators that her grandmother's blood got on her arms and clothing as she tried to help the dying woman.

Defense attorneys say that if Harris is convicted, they'll present evidence that she was mentally ill and can't be held criminally responsible.