Heidi Campisano was a surrogate mother who gave birth to a baby which was the child of Adrian Nelson and his wife, Sara.
At some point, Joseph Barnes, the father of one of Heidi's victims, Nicholas Barnes got greedy and decided to kill Heidi before kidnapping the baby. But he cut it too close as the brakes of the car Heidi was driving gave out and as such, Heidi gave birth to the baby almost immediately before Barnes gave her a vicious beating, quite possibly in revenge for Heidi hurting his son.
Heidi eventually succumbed to the fatal injuries while Barnes took the baby she had been carrying for the Nelsons and held it for ransom.
During a search of the crime scene which had a dead Petty Officer named Christopher Munoz whom Barnes had killed before stealing his car, NCIS Medical Examiner Donald Mallard found Heidi's body, sending the Major Case Response Team on a hunt for the missing baby and Heidi's killer.