Defenders on Wednesday called their first witnesses in the Christine Smart murder trial: two forensic experts who testified regarding soil samples taken from Ruben Flores’ property in Arroyo Grande.
The defense also filed two motions for a mistrial. Both were denied.
On Wednesday, for the second day in a row, the defense requested a mistrial. Monterey County Superior Court Judge Jennifer O’Keefe denied a similar motion to vacate the trial Tuesday, as well as a motion to dismiss.
David Carter was the first expert witness called by the defense to challenge the evidence presented by the prosecution against Paul and Ruben Flores in the 1996 slaying of Christine Smart — specifically, a dirt stain found under Ruben Flores’ deck.
Ruben Flores is accused of helping his son hide Smart’s body.
Two archaeologists testifying for the prosecution earlier said on the stand that the soil disturbance beneath Flores’ deck resembled a grave.
Cindy Arinton, an archaeologist who specializes in human remains, testified that the stain resembled a pattern that occurs when the human body decomposes.
A defense expert says he’s never seen the stain below decks firsthand
Carter is director and professor of forensic science at Chaminade University in Honolulu. His doctorate focused on forensic taphonomy, which is the study of decomposition processes.
Carter, who has two decades of experience in the field, testified Wednesday that his review of the soil stain and soil samples taken from under Flores’ deck could not confirm the existence of a decomposing body.
Burial sites usually have other evidence, such as clothing, teeth, bones or hair, Carter said on the stand.
He said it was not visually apparent at the scene.
The stain, Carter said, looked more like a soil sample than a decomposition stain.
Carter said the soil pattern is a dark, wavy color that occurs when sandy soil has a high concentration of iron and clay.
On cross-examination, he testified that he had not heard of the pattern until he started working on the case, and had only read about the pattern and seen the photographs.
According to him, he has never seen a sample first hand.
In his report, Carter wrote that every soil sample from the excavated nets had high levels of iron, which can “accumulate in thin strips across the soil profile like lamellae.”
“The color changes could also be related to the decomposition of organic matter, but this is clearly not supported by the nutrient levels reported,” he said.
On cross-examination, San Luis Obispo County Deputy District Attorney Chris Pevrel noted that Carter wrote in his report that “visual characteristics of the soil do not support the presence of decomposing human remains.”
These include visual characteristics of tissue, bone, teeth or the body that would not be there if they were dug up, Pevrel noted.
Carter confirmed that these would be other characteristics, as color alone cannot confirm decomposed human remains.
Because soil microbes are some of the strongest decomposers, Carter said, it’s possible that biological evidence won’t be detected for long periods of time, depending on the environment.
Carter testified that he had seen photos of the soil stain and the excavation, and had reviewed law enforcement’s test reports. However, he did not do any first-hand analysis, he revealed.
Soil microbes are very rich, and even a shovel digging into the soil can change that, he said.
That’s what Peurel focused on — something that inspired Paul Flores’ defense attorney, Robert Sanger, to file two motions for a mistrial, citing “prosecutorial misconduct.”
In the non-jury hearing, Sanger argued that Pevrel assumed that Carter was not trying to obtain the samples. In fact, the attorney said, Carter asked Sanger for samples.
Pervrel denied Sanger’s allegations.
Pevrel said he only denied sending samples to an unaccredited lab, and reiterated that he was happy to send samples to an accredited lab. The prosecutor also said he was never told Carter wanted the samples personally.
O’Keefe denied both defense motions, saying it was a “matter of discovery.”
When the defense test case came up in late May or early June before the trial, she told the defense she could offer to sign the order, but they didn’t.
Blood tests “cause concern”, says witness
Next on the stand Wednesday was Elizabeth Johnson, who has been a DNA forensics consultant since 2003.
Johnson said she previously worked with DNA expert Angela Butler, who testified Monday and Tuesday during Smart’s trial.
Johnson said she was aware that Butler, a senior forensic DNA analyst at the Serological Research Institute in Richmond, was also an expert witness in the Smart case.
However, Johnson said, they disagreed about the validity of the human blood test used on the soil samples.
Johnson said the test results were “concerning” because there was no validation of how the tests react with blood on the soil and the test results were inconsistent.
Butler testified Tuesday that validation studies were not necessary because there is no way to test for every judicial environment.
“You need to be sure that they are valid tests and you need to know the conditions when they work and when they don’t work,” Johnson said Wednesday.
Johnson said she emailed a scientist at Serotec, a German company that makes the human blood protein test Butler used, asking for a review of the research.
Christian Stadler, a scientist at Serotec, responded that he had no research on how the test works on blood samples that have been in soil for more than 20 years.
He said the test can react “invalid” if the pH is too high or too low, but the buffer required to be used with the test should prevent this result.
She said Johnson’s biggest concern was that subsamples of soil in the same vial gave different results.
For example, one sample gave three positive results, two weak and one negative Butler’s testimony on Monday.
“For some of these soil tubes that were between 40 and 140 grams, the results were inconsistent,” Johnson said. “There was no reproducibility in a single tube of soil.”
She added that the recent testing of samples from the 2021 excavation, which returned negative results, “indicates the inconsistency and irreproducibility of the test results.”
Court adjourned for Wednesday at 4:15 p.m., and Johnson is expected to finish his testimony Thursday morning.