The Bothell woman, 43, pleaded guilty Thursday to one count of second-degree murder.
Davidson, who has struggled for years with mental illness, submitted a written plea statement that says she has no independent recollection of killing Lila Donaldson on Oct. 27, 2012.
During Thursday's hearing, she made clear she understood the consequences of her plea, which will send her to prison anywhere from 10 to 20 years under state sentencing guidelines.
Davidson didn't admit responsibility for the killing, but acknowledged the evidence in the case likely would result in her conviction.
It was she who brought the violence to the attention of police. She called 911, first asking to be taken to a psychiatric hospital.
Once officers were at the home, she said they ought to check on her mom. When they attempted to go inside, however, she slammed the door shut, saying it was "really bad."
An officer kicked open the door and found Lila Donaldson, dying from a head wound.
Investigators later determined she'd been struck with a heavy, glass drinking mug.
Davidson at the time had been barred from her mother's home after violating a no-contact order. That was issued after a June assault on the older woman.
Her mom in August had urged the court to let her daughter return home, saying Davidson was her caregiver. She also said the younger woman had been doing well in recent months after agreeing to take medications.
After her arrest, Davidson told police that she knew she was taking a risk returning home.
Judge George Appel scheduled sentencing for Nov. 25.
Scott North: 425-339-3431, firstname.lastname@example.org
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