The defense lawyer for a man charged with raping and killing a University of New Hampshire student has spent his first day cross-examining the state’s star witness by trying to show she was possessed by imaginary characters she had created.

Defense attorney Joachim Barth also said 20-year-old Kathryn McDonough changed her story and shifted the blame from herself to her ex-boyfriend, 31-year-old Seth Mazzaglia, just to get a reduced sentence.

“And while you were on her for 10-15 minutes you described she had a seizure and that she subsequently died,” Barth said.

Mazzaglia is charged with first-degree murder in the October 2012 death of 19-year-old Elizabeth “Lizzi” Marriott of Westborough, Massachusetts.

Prosecutors say he and McDonough dumped her body in a river. It has not been recovered.

McDonough testified Thursday the imaginary characters she began creating during childhood were just “masks” to help her get through difficult situations.

The Associated Press contributed to this report.

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