Sufficient evidence existed that the minor was at risk of injury where she suffered nonaccidental injuries while in mother’s custody. The infant minor’s parents were separated, and the minor lived with each parent for one or two weeks at a time. Father reported that when the minor was dropped off at his house, he discovered bruising and bite marks on the minor’s body. Mother denied causing the injuries. A medical report found the injuries to be nonaccidental, and the bite marks to be from an adult. A petition was sustained which alleged that the minor was at risk of injury in mother’s custody. On appeal, mother contended that there was insufficient evidence supporting the juvenile court’s finding that the minor had suffered or was at risk of suffering physical harm inflicted by mother. The appellate court rejected the argument and affirmed. Mother and her roommate were the only people who took care of the minor at the time the minor sustained the injuries. Mother’s explanations for the injuries were not plausible. The juvenile court did not err when it applied the presumption under section 355.1 that the minor was a person described by section 300, subdivision (a). Nor was the presumption rebutted by mother’s evidence.