JACKSONVILLE, Fla. - A teenager accused of killing his grandmother nearly two years ago pleaded guilty Wednesday to a charge of second-degree murder, one month before he was to go on trial. Mott was 15 when he was accused of killing 53-year-old Kristina French (pictured, right) and burying her in his father's backyard in Neptune Beach days before Thanksgiving 2017. French had been taking care of Mott while Mott's father was on vacation. Investigators issued a murder warrant for him four days later and Mott was extradited to Jacksonville on Dec. 5, 2017. Investigators said Mott confessed to killing French.