MONCTON, N.B. -- Testimony has started at the trial of a woman charged in the brutal murder of a young New Brunswick man in December 2015.

Marissa Shephard has pleaded not guilty to first-degree murder and arson with disregard for human life in the death of 18-year-old Baylee Wylie of Moncton.

His body was found by firefighters in a burned-out triplex in Moncton where he had been tied to a chair, beaten and stabbed more than 100 times.

Twenty-one-year-old Devin Morningstar was found guilty of the same charges in November 2016 and is serving a life sentence.

Another man, 20-year-old Tyler Noel, pleaded guilty in May 2017 to second-degree murder and arson with disrespect for human life and was also given a life sentence.

The 22-year-old Shephard was arrested March 1, 2016, and has been in custody ever since.