Crime Library: Criminal Minds and Methods

Kevin Neal, Convicted of Murder by Forensic Entomology

Battle Over Bug Evidence

At the time of Kevin Neal's trial, there were fewer than ten people in the United States who were board-certified by the American Board of Forensic Entomology, and the fact that two of the Board's leading practitioners were testifying in his trial clearly demonstrated the importance of bug evidence in the case. Dr. Neal Haskell, who testified for the state, was one of the first people to ever study entomology for forensic purposes, and Dr. Robert Hall, who was about to take the stand to rebut his testimony, was the chair of the entomology department at the University of Missouri and had served on Haskell's doctoral committee.

To say that this was a battle of the field's giants was not an understatement.

Dr. Hall took the stand several days after Dr. Haskell testified, and the defense wasted no time in attacking Haskell's conclusions.

Unlike Dr. Haskell, who based his conclusions on the serial theory of insect activity — where scientists theorize that a corpse is colonized by successive "waves" of insects — Dr. Hall was only willing to accept the more conservative temperature-based model. In his opinion, the timing of when any particular species of arthropod would show up was simply too variable to use for drawing scientific conclusions.

Graphic depicting successive waves of fly infestation
Graphic depicting successive waves of fly infestation

"Do you believe there is any conclusion that can be reached from the absence of the secondary screwworm at the same time that the pupa cases from the black blow fly are found at the scene?" defense attorney Marc Tripplett asked.

Dr. Hall was quite blunt. "No."

Tripplett pushed the point further and asked Hall what conclusions he could draw based on the evidence that was present.

"The only conclusion that I can reach is that the temperature development of the black blow fly is such that about 215 accumulated degree days on a base temperature of 10 (degrees Celsius) is required for that fly to go from the stage that the female deposits the egg, to the point at which the adult fly leaves the pupa case that then stays behind," Hall answered.

Assuming that the temperature at the Dayton airport accurately reflects the temperature at Nettle Creek Cemetery — a big assumption, the defense expert pointed out — Hall then said that he drew an entirely different PMI than Haskell did.

"The decedents must have been at the site at least long enough for the insects to grow up at the stage collected, and that would have been from about the first week in September," he said.