A 25-year-old woman accused of murdering her 55-year-old mother this week at their Halawa Heights home told police that she had to kill her mother "before she killed me," according to a court document.

Carol K. Weidman was charged last night with second-degree murder and was held on $50,000 bail. If convicted, Weidman faces a mandatory prison term of life with the possibility of parole.

Weidman was arrested early Thursday morning after her mother's lifeless body was found at their Pa'ihi Street home by the older woman's boyfriend. The boyfriend told police both women were home when he left the residence at about 7 p.m. When he returned at about 11 p.m., he found the victim bleeding on the floor, according to a police affidavit filed in Honolulu District Court.

The man told police Weidman was in a room directly across the hall from where her mother lay, the affidavit said. He said when he asked Weidman if she heard or saw anything, she said she didn't.

According to the affidavit, the police detective asked Weidman if she would mind going to the police station to be interviewed, and Weidman said she didn't.

The detective had an officer take Weidman to the Pearl City police station, where Weidman began talking to the officer — who was sitting in the lunchroom reading a book — about the killing.

Weidman told the officer that "her mother had tried to kill her brothers and her father, and Carol Weidman did not want her to come after her, so Carol Weidman went after her mother first," the affidavit said.

When a police investigator told Weidman she was under arrest, Weidman said: "My dad always told me that my mother tried to kill him and my two brothers before they got divorced; and that is always in the back of my mind. I had to kill her before she killed me. It was always on my mind."

The victim died of manual strangulation and stab wounds to her neck and chest.

Police recovered three bloodied knives from the scene.

Weidman has no prior criminal convictions in Hawai'i, police said.

She is expected to make her first court appearance Monday at District Court, with a preliminary hearing tentatively scheduled for Wednesday.

Reach Lynda Arakawa at larakawa@honoluluadvertiser.com.