Sixty-two-year-old Kathleen Marie Steele was arrested Thursday on charges of aggravated manslaughter of a child and neglect after her six-year-old son beat her 13-day-old daughter to death while she left them in a hot car for almost 40 minutes.Steele's newborn baby, also named Kathleen, was in good health Monday morning when the the mother took her to see a pediatrician, bringing along her young sons.As they were leaving the doctor's office, Steele's oldest son, dropped his mother's phone - shattering the screen, so Steele drove to a cellphone repair store in St. Petersburg to get the phone fixed.Instead of bringing her children into the store with her though, she turned the car off, rolled up the windows and left them inside alone for a half hour (temperatures went as high as 81 degrees on Monday). The 13-day-old baby started to cry while being stuck in the hot car, Sheriff Bob Gualtieri told the media. Frankie took the baby out of her car seat and eventually started to beat her to make the crying stop. When the 6-year-old boy was questioned by the police, he not only confessed to what he had done but described the horrific incident in great detail, the sheriff also said.“I took the baby, and I slammed her like this, and slammed her down, and pushed her up into the ceiling,” the little boy said, according to Sheriff Gualtieri.“What he was talking about when he pushed her up into the ceiling, he was holding her up, then he said he was flipping her this way and flipping her that way and she would fall. The way he was describing it is he was tossing that baby around like a ragdoll,” the Florida sheriff added. “The best way I can describe it is, he pummeled her. I’m telling you, this baby’s face was a mess. There was no mistaking the condition that this 13-day-old infant was in.” Steele didn't even call 911, authorities said. Instead, she called a neighbor who is a nurse, who recognized the baby was dead. The nurse performed CPR until paramedics arrived.