Prosecution's bug expert struggles on stand
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SAN DIEGO — The insect expert prosecutors hoped would destroy David Westerfield's chances for acquittal stumbled badly during his turn on the witness stand Tuesday, capping confusing, overly technical testimony with the admission he made basic math errors in his findings.
Madison Lee Goff, one of the most experienced scientists in the small field of forensic entomology, blushed a deep red as a defense lawyer for the man accused of killing Danielle van Dam repeatedly confronted him with five separate errors in data he used to analyze bugs collected at the 7-year-old's autopsy.
"I made a mistake adding," said Goff, the chair of the forensic science department at Honolulu's Chaminade University and one of only nine certified forensic entomologists in North America.
Entomology has become a battleground as Westerfield's two-month long capital murder trial draws to a close. The strongest evidence for the defense comes from this field in which insect specialists use the age of maggots and flies decomposing a body to help determine a time of death. Danielle, abducted from her bedroom Feb. 1, was missing 26 days and when her body was finally found, the medical examiner was unable to pinpoint when she was killed. Two forensic entomologists hired by the defense said their analyses suggested her body was dumped along a roadside in mid-February, long after Westerfield was under constant police surveillance.
Prosecutors, who have a pile of other evidence against Westerfield, including hair, blood and fingerprint evidence, hired Goff soon after the first defense entomologist testified.
Goff said Tuesday he disagreed with the conclusions of both defense experts, but the time frame he offered, Feb. 9 to Feb. 14, was only slightly earlier than theirs and did not neatly fit the prosecution's theory that Danielle was killed between Feb. 2 and Feb. 4 while Westerfield claims he was on a solo camping trip. Prosecutor Jeff Dusek had to question his own expert in much the same way as he cross-examined the defense experts, hinting that variables in the weather and the disposal of Danielle's body cast doubt on the certainty of any entomological findings.
Goff agreed that very hot, very dry weather conditions in San Diego in February might have mummified Danielle's 58-pound body almost immediately and that flies may not have been attracted to the desiccated body. A forensic anthropologist, called by the prosecution last week to cast doubt on the bug evidence, said the insects may have arrived later and only after coyotes and other animals began scavenging her body and Goff said this scenario seemed possible.
He also said a covering, such as a blanket, might have kept flies at bay initially. No covering was found and Goff later said the longest delay by such a shroud was two and a half days.
Much of his testimony was a detailed view into the mathematical nuts and bolts of his conclusions. Goff did not look at the bugs himself. Instead, he reviewed photos and the reports of the defense experts. He told jurors he came up with four separate time lines based on two different temperatures at two separate locations, a golf course a mile and a half from the crime scene and National Weather Service station farther away.
Goff's testimony bounced between these four sets of findings and even after he said the lower temperature and the weather service station provided the most reliable, appropriate date, it was often unclear which findings he was referring to. He peppered his speech with entomological jargon like "accumulated degree hours" and referred to blowflies by their the Latin names. He talked about temperatures in Celsius degrees, frequently prompting Dusek to ask for a Fahrenheit translation. Much of his work seemed lost on jurors, who stopped taking notes early on in his testimony.
On cross-examination, defense lawyer Steven Feldman grilled him about the way he calculated the day-to-day temperatures which dictate how fast an insect grows. Goff explained the process, but then Feldman handed him a pocket calculator and asked him to review his findings. With the courtroom completely silent, Goff added rows of figures and discovered his errors. Feldman asked him if the mistakes effected the accuracy of his estimates and Goff said they did. Several jurors picked up their notebooks and began writing rapidly.
A few minutes later, under questioning by Dusek, Goff said the slip ups made little difference in the ultimate conclusions. And as he had earlier in his testimony, he emphasized to jurors that his was an extremely narrow study of bugs, not a "stopwatch" for determining time of death.
"We're establishing a minimum period of time the insects have been feeding on the body," said Goff.
"Are you establishing a time of death?" asked prosecutor Jeff Dusek.
"No, that's outside our area of expertise," said Goff.
Danielle's parents, Brenda and Damon van Dam, watched most of the testimony from the back row of the courtroom, occasionally flinching as Goff described the condition of their daughter's remains.
The prosecution rested its rebuttal case after Goff's testimony. There will be no witnesses Wednesday and the defense will put on its sur-rebuttal case Thursday. Closing arguments could happen as early as next Monday.
Also Tuesday, a lab technician testified that orange clothes some law enforcement officers wore when searching Westerfield's house were not the source of fibers found in both the defendant's home and in Danielle's necklace.
The trial is being broadcast live on Court TV.
A hunting we will go...