A Lawrence woman pleaded guilty last week and received a 50-year prison sentence for planning the 2009 murder of her former boyfriend in southern Missouri.

Annette Cross, 32, was arrested in Lawrence on a warrant in September 2009 and charged with first-degree murder and other charges in the death of her former boyfriend, Andrew Day, 37. Prosecutors in Howell County, Mo., accused Cross of driving her brother, Dale Cross, of Hannibal, Mo., to Day’s home outside Mountain View, Mo., where Dale Cross shot him. They then burned down the residence, and investigators found Day’s body inside.

“It was her plan. It was her motive to kill him, and she dragged the other three into it,” said Rizwan Ahad, an assistant Howell County prosecuting attorney. “She and her brother drove to Mountain Valley to kill him.”

Annette Cross pleaded guilty Friday to second-degree murder, armed criminal action and second-degree arson. A judge sentenced her to serve consecutive 25-year sentences on the murder and armed criminal action counts. She also will concurrently serve seven years in Missouri prison on the arson charge.

Ahad said prosecutors made the offer to Annette Cross for the pleas and sentences to match the sentence Dale Cross received about a month ago. A jury convicted him last year of the same three charges.

The Crosses’ mother, Joann Cross, 55, and Dale Cross’ fiancee, Kristin Smith, 22, both of Hannibal, are serving 11-year and 10-year prison sentences respectively after they pleaded to conspiracy for their involvement in buying the gun, Ahad said.

Ahad said Annette Cross is expected to be transferred to custody of the Missouri Department of Corrections soon.