Scientists armed with soil vapor detection equipment and ground radar were at the home of the mother of Kristin Smart’s killer the other day, searching for secrets in the soil 30 years after her disappearance.
On Thursday, soil engineer Tim Neligan and former FBI chemist Brian Eckerd, with assistance from local soil scientist Steve Hoyt, probed into the ground near Susan Flores’ property in the center of the Arroyo Grande. They were also joined by a team of ground radar experts who scanned the heavily concreted property, and assisted the San Luis Obispo County Sheriff in serving a search warrant at the home.
“We’re looking for answers,” Neeligan said, “We all want to give Dennis and Stan Smart some peace after all these years.”
Susan Flores’ son, Paul Flores, was last seen with Smart as the two headed to her dormitory at Cal State San Luis Obispo after a 1996 Memorial Day weekend party. He was eventually declared dead, but his remains were never found.
Decades passed before Flores was arrested and prosecuted. He was sentenced to 25 years to life in prison for Smart’s murder three years earlier. But, insisting on his innocence, he never provided any space for her remains.
Kristin Smart disappeared almost 30 years ago, in May 1996.
(Record via Tribune News Service)
Three years ago, Neligan and his colleagues, working in the backyard of a neighbor of Susan Flores, used soil vapor sampling to detect volatile organic compounds they say could be linked to the decomposition of human remains. Neligan, an environmental engineer from San Clemente, met Smart in college. She remembers him knocking on her door and asking to use her landline phone.
Neligan was visible again in that yard this week. They pushed a small instrument with a long straw-like attachment, known as a soil vapor probe, into the earth about 3 to 5 feet. Any gas encountered in the probe was collected by vacuuming, then sealed in a canister. The extracted volatile organic compounds can then be sent for analysis.
Neligan said that, since 2023, they have refined the science and are preparing to publish an academic paper on the unprecedented methods of locating the body in soil.
But perhaps more importantly, in September 2023, he helped federal investigators locate two bodies in Yakima, Washington, said Tim Perry, a former federal prosecutor and top Department of Homeland Security official. According to Neligan, one of those bodies, that of a pregnant woman, was found just 10 feet from the spot where his investigation revealed the human remains lay as he worked with Homeland Security Investigations.
Tim Neligan drops soil vapor samples taken from the backyard of a neighbor of Susan Flores into a laboratory in 2023.
(Brian Eckenrode)
Since then, he has worked with control samples and actual cadavers buried in soil in body farms to further refine his methods. Some of the actions resulted in a search warrant being served Wednesday for a property in the 500 block of East Branch Street in Arroyo Grande.
San Luis Obispo County Sheriff Ian Parkinson, along with investigators and experts, attended the home Wednesday morning shortly after a detective served a search warrant on Susan Flores.
“This investigation is related to the disappearance of Kristin Smart,” the sheriff’s office said in a statement. “This activity is the result of a search warrant signed by a Superior Court Judge. The Sheriff’s Office is committed to bringing Kristin home to her family.”
That warrant was based partly on the work of Neligan’s team. Following their initial findings, the Sheriff’s Office asked for additional data and academic research to support their new method of detecting remains using soil vapor.
Although the practice is still in the theoretical research stage, scientists have spent two decades studying the chemical compounds associated with the breakdown of the human body.
Tim Neligan believes that soil vapor probes, like the one in the picture, could help locate Kristin Smart’s remains.
(Christina House/Los Angeles Times)
The San Luis Obispo Sheriff’s Office previously said authorities were also in contact with the FBI about researching the men. The science at the time was unproven and had never been used in any criminal proceedings, but the group told The Times they were confident in their findings.
San Luis Obispo County Dist. Attorney Dan Dow said his office has made a commitment to the Smart family and this community: to bring Kristin home.
In a statement, Dow said his Bureau of Investigation and Assistant Dist. Atty. Eric Dobroth helped obtain authorization for the warrant.
He added, “While those responsible for Kristin’s death – and those with information about her whereabouts – may respond at any time, we are strongly committed to using every legal tool available to support her family until Kristin’s remains are located and brought home.”
Paul Flores was arrested by San Luis Obispo County Sheriff’s deputies in April 2021 in connection with the murder of Kristin Smart.
(San Luis Obispo County Sheriff’s Office)
The public’s on-again, off-again interest kept Smart’s disappearance sporadically in the news, but a podcast called “Your Own Backyard” started in 2019 by Chris Lambert shed new light on the cold case.
In November 2019, Neligan began researching how bodies decompose in soil. Two months later, he recruited Shoyt, another Cal Poly graduate with a doctorate in environmental science who had built a business testing soil samples on the Central Coast. Eckenrode, a retired FBI forensic scientist and expert on human decomposition, joined them in 2021.
Authorities had repeatedly searched the backyards of homes personally owned by Paul Flores’ parents. Sheriff’s deputies also used ground-penetrating radar and cadaver dogs to search Ruben Flores’ Arroyo Grande property in 2021. No remains were found, but a month later, both of Flores’ men were arrested and charged in connection with Smart’s murder.
In 2023, the three locked themselves in Susan Flores’s Arroyo Grande home, a short distance from Ruben Flores’ home. The property has been the subject of search warrants in the past – including one stemming from civil litigation with the Smart family.
Susan Flores was never charged in connection with her son’s crimes. During the search three years ago, he said he did not kill Smart and that his family did not know the whereabouts of the missing student.
Attorney Harold Messick, who secured a not guilty verdict on Ruben Flores’ accessory charges, told The Times in 2023 that the idea that a body could be in Susan Flores’ yard is “ridiculous”.
