SPRING HILL — Just before 11:30 Thursday morning, Michelle Williams got a call at work from her husband. Their baby, 9-month-old Kobe, had fallen into the pool. He wasn't breathing.A co-worker drove Mrs. Williams home. When she arrived, an ambulance had already left with her baby inside. She got back into the car to follow, to be with her baby. But deputies told her to stay, to wait.She couldn't see her husband yet, either, they said. He was too distraught.Mrs. Williams lit a cigarette. Her hands trembling, she took short drags between long sobs and deep, heaving breaths. Wearing blue hospital scrubs, she paced beneath a magnolia tree in the gravel driveway next to her front yard. Hernando County homicide investigators stepped beneath the crime-scene tape surrounding her home on Thornberry Drive."This," Mrs. Williams said to a deputy, "is the worst nightmare a mother could ask for."Mrs. Williams and her husband, Tywane, are certified nurses' assistants. They work separate shifts so one can always stay home with their four children, all elementary school age or younger. Neighbors say the Williamses, both 31, are new to the area and are wonderful parents."I can't get freaking answers," Mrs. Williams, on her second cigarette, said to an investigator. "All I want is answers."A detective emerged from the home and stepped past a pair of strollers on the front porch. He motioned Mrs. Williams over. She walked into the house and, seconds later, the people gathered outside heard screams so steeped in pain that veteran deputies bowed their heads and turned away.Kobe had died at the hospital.Investigators would later say that the child had slipped out a sliding door that had been left open."Don't tell me it's my boy," Mr. Williams shouted from inside the home. "Please, get me out of here."He stumbled outside, weeping and hyperventilating. Next to a detective's Ford Taurus, he fell to his knees. One hand braced against the ground and the other covered his face. His wife, in a haze, staggered out behind him.Mr. Williams crumpled into the back of the detective's vehicle. He gripped a handkerchief in his right hand, the headrest in his left. His wife sat next to him.He tried to explain, speaking with such force that his words could be heard a block away.I was just gone for five minutes.I was changing one of the other kids' clothes in a different room.Somehow, the back door was opened and Kobe got out. He fell into the pool. I don't know how.I couldn't save him.Times researcher Carolyn Edds contributed to this report. John Woodrow Cox can be reached at [email protected] or (352) 848-1432.