An archeologist Tuesday testified about her findings at two excavated sites, including one which contained an “odd stain,” during searches for Kristin Smart's remains at the Arroyo Grande home of Ruben Flores in March and April.

Cindy Arrington and her colleague Phil Hanes were hired by the San Luis Obispo County Sheriff’s Office to conduct searches using ground-penetrating radar for possible burial plots on the property, during warrants executed on Flores’ home in the 700 block of White Court.

In one of the holes that were dug, Arrington described a lack of consistency in the sandy soil and a “bathtub ring” along the side of the wall, which she said was a “good indication” of a human burial site and that its contents was later removed.

“When you’re looking for human remains, one of the first things you want to look for is staining,” Arrington said, adding that the dark stain did not match the surrounding soil. “I did not say ‘eureka!’, ‘a-ha!’ but as an archeologist, it’s indicative of human decomposition.”

The searches included two cadaver dogs that exhibited changes in behavior but no confirmed alerts on the same strips of land under the deck.

Search warrants were also executed at the same time on the San Pedro home of Paul Flores, who is accused of killing Smart, the 19-year-old Cal Poly freshman who went missing on May 25, 1996. 

Smart was last seen with Paul Flores near the intersection of Perimeter Road and Grande Avenue, just steps away from their dorms, at about 2 a.m., according to witness Cheryl Manzer, who walked with them from a party before splitting off from the pair. 

Paul Flores, 44, is charged with Smart's murder. His 80-year-old father, Ruben Flores, is charged with accessory to murder after the fact and is accused of hiding her body.

Both were arrested and charged in April. They have pleaded not guilty.

Arrington and Hanes took the stand Tuesday during the preliminary hearing for Paul and Ruben Flores, which began on Aug. 2.

They both work for Sacramento-based Natural Investigations Company, which was hired by the Sheriff’s Office to conduct searches on March 15 and 16, 2021. Both indicated recent successes with law enforcement in other cases. 

Hanes, who specializes in the practice of remote sensing using ground-penetrating radar, was the first witness called by Deputy District Attorney Christopher Peuvrelle to describe the search using his equipment.

Hanes described the GPR as an “emerging” technology that’s used to detect voids in soil and was used to conduct nearly a dozen grid searches on the property, including Grid 1 and Grid 3 underneath the deck, which revealed anomalies in the soil.

He added that further investigation, or a process called “ground truthing” that includes digging, was needed to explain what those anomalies were.

Using data taken from a 4-feet by 6-feet plot in a space hardly tall enough for a human being to stand, Hanes mapped a 3-D model of the site showing a blue blob extending several feet down, indicating the anomaly, that was encapsulated by white space, which was the surrounding soil.

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Next, Peuvrelle displayed a “time slice” graphic model of the data from Hanes' radar search on the strip under the deck that showed heavy shades of orange and some yellow in one spot at the end of the graph, although most of the graph’s color was blue.

“We don’t know what is buried there until we dig,” Hanes said. “[The] anomaly could be air introduced into the soil. There could be any number of specific reasons.”

After Hanes, Arrington testified about her follow-up digs of the anomalies. 

Arrington, who is a registered professional archeologist, said grids 1 and 3 were the only grid searches that showed a “clear subsurface disturbance.”

Grid 3, which contained a 4-feet by 5-feet, and 3-foot-deep anomaly and was located under the deck in a spot facing the southeast, did not show any signs of human decomposition, according to Arrington.

Arrington testified that Grid 1 lacked the layered characteristics of soil that had been undisturbed and had dark stains showing “something was there," which had leaked fluid and was later removed. She added no bones, hair or other human body parts were located at the site. 

After Sheriff’s officials alerted Arrington to the soil stains approximately one-and-a-half feet to two feet down, Arrington said she sampled the darkest stain on the downward portion of the sloped area, where she believed the liquid pooled.

Soil samples taken from the site indicated human blood, although DNA could not be extracted, according to court documents filed by Peuvrelle.

But Arrington said the stains could also indicate decomposition fluid. She testified that although she is not an expert in human decomposition, she learned from past work with a scientist at the Forensic Anthropology Center in Tennessee, also called "the body farm," that the skeletalization process could take up to decades depending on soil conditions.

Arrington, who found evidence of Native Americans at the 2002 archeological dig at Yerba Buena Island, said decomposition stains can remain for thousands of years. 

Bob Sanger, Paul Flores’ attorney, asked how the stained soil could be intact after it was excavated. Arrington responded by saying the stain along the wall of the site remained consistent, but not as they kept digging deeper.

The preliminary hearing continues at 9 a.m. on Wednesday in Superior Court.