Nine One One — J.D. Webb

Jennifer Menlo loves her 911 dispatcher job, and especially loves helping people. But one desperate call from a brave seven-year-old leaves her with a yearning to do more, even though that's strictly prohibited by the police department. The boy discovers his mother's body and when he calls 911 for help Jen discovers the boy's home is not far from where she lives. She doesn't hesitate to offer more than a helping hand.
Little does she know that a murderer who has killed once will readily chose a second victim if that person threatens to reveal the killer's identity.