But four weeks ago, when the first victim was discovered, I recovered no saliva from the two bite marks on the body. I figured the killer for an organized offender who washed the saliva out of his bites to prevent recovery of DNA evidence. But a week later, when the second victim was found, my theory was blown out of the water. I recovered saliva from two of four bite marks left on the corpse. This raised the possibility of a different-and disorganized-killer. But by using reflective ultraviolet photography and scanning electron microscopy on the bite marks, I concluded that the same killer had indeed murdered both victims. Ballistic analysis of the recovered bullets supported my conclusion, and six days later, when the third victim was murdered, my opinion was confirmed beyond doubt by DNA recovered from the bite marks left on that body. The same killer had murdered all three men.

The importance of this cannot be overestimated. The baseline criteria for classifying a serial murderer are three victims killed by one person, each victim killed in a different location, and a cooling-off period between the crimes. I had helped prove what I’d known from the moment I saw the first victim. New Orleans had another predator on the hunt.

My official responsibility ended with matching the bite marks, but I wasn’t about to stop there. As the New Orleans Police Department joined the FBI in the uneasy marriage of a task force, I began to analyze other aspects of the case. In sexual homicide, the murderer’s selection criteria for his victims hold the key to every case. And like all serial murders, the NOMURS killings-so dubbed by the FBI for “ New Orleans murders”-are at root sexual homicides. Something always links the victims in these cases, even if it’s nothing more individual than geographic location, and that link draws the predator.