Timera Branch is charged in the 2009 death of 17-year-old John Keyes, III. She's accused of running her car into Keyes and ramming the teenager into a building.
ABC7's news partner The Daily Herald reports an emotional Branch testified that she struck Keyes, but she did not know why she did it.
Prosecutors say she went after Keyes to teach her son, Lecorbek Benion, 17, how to stand up for himself. Benion is also charged with murder. He will be tried separately.