A Miami-Dade woman was booked into jail Wednesday after one of her sons used an unsecured gun to shoot and kill his 4-year-old sister last month. The mother’s boyfriend, who is accused of leaving the gun unattended, was arrested shortly after the shooting. Krystal Banegas, 24, was charged with child neglect causing great bodily harm, and three counts of child negligence for each of her surviving sons who witnessed the shooting. Her boyfriend, Quavanta Demettris Ennels, 25, has been charged with aggravated manslaughter of a child, three counts of child negligence, and possession of a weapon by …