NEW CITY, N.Y. (CBSNewYork/AP) — A third woman admitted her part Thursday in the killing of an activist from Rockland County – leaving only the victim’s daughter-in-law in Florida fighting charges.

The Rockland County District Attorney’s office said Andrea Benson of Washington, D.C., pleaded guilty Thursday to second-degree murder and will be sentenced to 20 years in prison. She has been charged with first-degree murder.

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The victim was Peggy Nadell, 80, who was found dead in her Valley Cottage home on Jan. 25.

Her daughter-in-law, Diana Nadell of Cutler Bay, is accused of first-degree murder. She has pleaded not guilty.

Prosecutors said she hired Benson to help her kill her mother-in-law so she could receive an inheritance.

Her husband, the victim’s son, is not charged.

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Two other women — Tanisha Joyner, 26, and Eltia Grant, 24 — have pleaded guilty to lesser charges in connection with false alibis.

Diana Nadell is due back in court on July 14.

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