Frustrated prosecutor swats at final bug expert
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SAN DIEGO — David Westerfield was sitting in the defendant's chair, but forensic entomology was on trial Thursday.
Prosecutor Jeff Dusek, whose seemingly unshakeable case against Westerfield for the murder of Danielle van Dam has been jostled by this tiny, somewhat obscure scientific field, poured out his frustration on the last of three insect experts to testify for the defense.
Like his colleagues before him, forensic entomologist Robert Hall of the University of Missouri told jurors that the age of bugs decomposing Danielle's remains suggests Westerfield could not have dumped the 7-year-old's body along a roadside last February.
Dusek, with sighs, long stares at the ceiling and a tone that often mixed disgust with disbelief, railed against Hall's methods and the inexact nature of the field, in which experts given the same bug samples and weather data can differ in their conclusions by days and even weeks.
In one exchange, Dusek asked bitterly, "If you give an X-ray of a suspected broken arm to four qualified experts, would you expect them all to read it the same?"
"I don't know. I'm not a radiologist," replied Hall, whose mild-manner and stammering answers contrasted sharply with the prosecutor's intensity.
Three of the nine certified forensic entomologists in North America have testified in the case, as well as a local expert who is well-respected but not certified. They each offered slightly different ranges for the first arrival of insects at the death scene. Most placed them in mid-February.
"How can everyone come to different numbers in your field?" Dusek demanded.
Hall said "biological variation" in the insects led to some differences in results, but he claimed there was an overwhelming and unusual "concordance" among the experts that Danielle's body was first infested in mid-February, when Westerfield has an air-tight alibi.
"My conclusion would be the estimates are more consistent than inconsistent," said Hall.
"Are you saying close enough for a murder case?" Dusek shot back
"No — ," Hall uttered before Judge William Mudd ordered him not to answer the question further.
Some of the jurors, who have heard days of testimony about maggots, blowflies and puparia, seemed bored by the exchange while others continued taking detailed notes. One male juror seemed to sympathize with Dusek and shook him head in agreement as the prosecutor became impatient with Hall's long-winded answers.
Hall may be the final witness the panel hears. Westerfield's lead attorney, Steven Feldman, said the defense will decide this weekend whether to call one more witness, a forensic anthropologist to testify briefly about the time of death issue. If the defense does not call that expert, lawyers will deliver closing arguments Tuesday. If they do, he will testify Tuesday and arguments will begin Wednesday morning.
Westerfield, a 50-year-old engineer who lived two doors from the van Dam family in the upper middle class suburb of Sabre Springs, faces the death penalty if convicted. Someone snatched Danielle from her canopy bed during the night of Feb. 1. Searchers found her body Feb. 27 on the trash-strewn roadway about 25 miles from her house. Her body was too badly decomposed to determine when or how she died, but prosecutors theorize Westerfield raped and suffocated her and then dumped her body during a meandering 560-mile road trip in his recreational vehicle the weekend after her disappearance.
The trial initially focused on significant trace evidence implicating Westerfield, including Danielle's blood, fingerprints and hair inside his RV, and on child pornography on his computers. But the insect testimony has dominated the later part of the trial. Dusek called his own bug expert Tuesday, but that entomologist made basic math errors in his calculations and ultimately gave findings that did not neatly fit the prosecution's theory.
Hall estimated that the first flies colonized Danielle's body, a process that can happen within minutes or hours of death, occurred between Feb. 12 and Feb. 23. Police began round-the-clock surveillance of Westerfield Feb. 5.
Hall also dismissed the prosecutor's suggestion hot, dry weather in February quickly mummified the exterior of Danielle's body, making it initially inhospitable to bugs. A forensic anthropologist testified for the prosecution last week that the flies and maggots may only have arrived after scavenger animals opened her body, skewing the insect evidence found at the scene.
Hall, however, said such a scenario was unheard of in forensic entomology.
"I'd expect fly activity to occur almost as soon as the body presented itself," said Hall, whose father, also an entomologist, wrote the textbook "Blowflies of North America. "
"Partial mummification has little or no effect on blowfly colonization," he added.
During his cross-examination, Dusek alternated between dismissing the field outright and delving into the most minute details of forensic entomologist's work. He quizzed Hall about each of the different formulas the scientist had merged to determine the growth rate of maggots and pointed out that one approach, when taken alone, indicated Danielle's body could have been dumped in early February when Westerfield's whereabouts are unaccounted.
Hall acknowledged Dusek was right, but said taking into account the other data sets yielded the most accurate result.
Dusek also grilled Hall about the lack of insect activity in the head area. Hall and the other entomologists said bugs are usually drawn first to the ears, eyes, and mouth, but Danielle's remains showed infestation primarily in the chest cavity. The prosecution contends this supports their mummification theory, and Hall admitted he could not explain why the insects stayed clear of the head.
Westerfield seemed to follow the testimony intently, leaning close as his defense lawyers conferred on questions for Hall. Brenda and Damon van Dam, Danielle's parents, sat in what have become their usual seats in the last row of the small courtroom.