Nearly three decades after Kristin Smart disappeared, San Luis Obispo County sheriff's investigators served a search warrant at the home of her killer's mother on Wednesday and prepared to scan and sample the land in search of her remains.
The Arroyo Grande house belongs to Susan Flores. His son, Paul Flores, was the last person seen with Smart as the two walked to his dorm at Cal State San Luis Obispo after a Memorial Day weekend party in 1996. He was sentenced to 25 years to life in prison three years ago for Smart's murder. But his body has never been found.
Three years ago, a group of scientists working in Susan Flores' neighbors' backyard using soil vapor samples detected the presence of volatile organic compounds that they say may be associated with decomposing human remains.
A sheriff's detective served Susan Flores with the search warrant shortly after 7 a.m., and also had access to a neighboring home where scientists detected the volatile organic compounds in 2023. The land has been registered before. Sources familiar with the investigation said the search is expected to last two days.
“The San Luis Obispo County Sheriff's Office is conducting an additional investigation into the property in the 500 block of East Branch Street in Arroyo Grande. This investigation is related to the disappearance of Kristin Smart,” the Sheriff's Department said in a statement. “This activity is the result of a search warrant signed by a Superior Court judge. The Sheriff's Office remains committed to bringing Kristin home to her family.”
San Luis Obispo County Sheriff Ian Parkinson, along with investigators and experts in ground-penetrating radar and soil science, showed up at the home Wednesday morning. Sheriff's officials confirmed that a search warrant is being served. The department said it will not comment beyond the statement.
Among those at the scene was Tim Nelligan, a soils engineer who, along with another scientist and an FBI research chemist turned professor, found signs suggesting human remains from data they collected in the area. The Sheriff's Department subsequently requested additional data and research from the academy to support its new method of detecting remains using soil vapor.
The group used a technology known as soil vapor sampling, which they say could detect volatile organic compounds associated with decomposing human remains. Although the practice is still in the stage of theoretical research, scientists have spent two decades studying the chemical compounds associated with the decomposition of the human body.
The Sheriff's Department has previously said officials have also contacted the FBI about the investigation. The science at the time was unproven and had never been used in any criminal proceedings, but the group told the Times they are confident in their findings.
The three-man team includes Timothy Nelligan, an environmental engineer who met Kristin Smart at Cal Poly San Luis Obispo in the 1990s.
(Brian Eckenrode)
Soil vapor sampling
Nelligan, an environmental engineer from San Clemente, met Smart in college. He remembered that she knocked on his door and asked him to use her landline.
“It was this attractive girl, 6 feet tall, who introduced herself as Roxy,” Nelligan said, referring to the nickname Smart used for a clothing brand she favored.
A week and a half later, he said, her disappearance appeared on all the local television stations.
Nelligan said she didn't know Smart's family, but she had always wanted to help.
Timothy Nelligan discusses the findings of Kristin Smart's case in his San Clemente office.
(Christina House / Los Angeles Times)
Intermittent public interest kept Smart's disappearance in the news sporadically, but a podcast called “Your Own Backyard,” started in 2019 by Chris Lambert, shed new light on the unsolved case.
In November 2019, he began researching how bodies decompose in soil. Two months later, he recruited Steve Hoyt, another Cal Poly graduate with a doctorate in environmental sciences who built a business on the Central Coast analyzing soil samples. Brian Eckenrode, retired FBI forensic scientist and human decomposition expert, joined them in 2021.
Authorities had repeatedly searched the backyards of homes individually owned by Paul Flores' parents. Sheriff's deputies even used ground-penetrating radar and cadaver dogs to search Ruben Flores' property in Arroyo Grande in 2021. No remains were discovered, but a month later, both Flores men were arrested and charged in connection with Smart's murder.
In 2023, the trio entered Susan Flores' home in Arroyo Grande, a short distance from Rubén Flores' home. The property had been the subject of search warrants in the past, including one arising from civil litigation with the Smart family.
Timothy Nelligan believes that soil vapor probes, like the one shown in the photo, can help locate Kristin Smart's remains.
(Christina House / Los Angeles Times)
Nelligan contacted neighbor Marcia Papich, whose fence abuts Susan Flores' backyard. After digging holes in the ground near the property line, Nelligan pushed a small tool known as a soil vapor probe, with a long straw-like attachment, three to five inches into the ground. Any gases the probe encountered were vacuum-extracted and collected, then sealed in a container. The extracted volatile organic compounds were then sent for analysis at a San Luis Obispo laboratory operated by Hoyt.
What appeared when those compounds were plotted with color on a column map and compared to dozens of nearby soil control point samples indicated the presence of a decomposing body, according to Eckenrode.
Susan Flores has never been charged in connection with her son's crimes. During the search three years ago, she maintained that he did not kill Smart and that his family does not know the whereabouts of the missing student.
Attorney Harold Mesick, who obtained a not guilty verdict on Ruben Flores' accessory charges, told the Times in 2023 that the idea that there could be a body in Susan Flores' yard is “ridiculous.”
He suggested that if authorities were looking for Smart's remains, they should expand their investigation into who really took her, maintaining that the Flores family had nothing to do with her disappearance. Mesick reiterated that nothing had ever been found in multiple searches of Susan and Rubén Flores' yards, and said authorities caused $30,000 in damage to Rubén Flores' property by digging under his deck, a search that turned up nothing.
Of course, investigators can't say what remains might be in Flores' yard or when they might have been buried. But the trio were confident that in 2023 they would have detected a body in the ground.
Now the search is back.
An earring found in the entryway of a home owned by Susan Flores, mother of convicted murderer Paul Flores, allegedly resembled the necklace Kristin Smart wears in photos on fliers and posters about her disappearance.
(Don Kelsen / Los Angeles Times)
The Branch Street home had first come under scrutiny a few months after Smart's disappearance. Mary Lassiter rented the pale blue two-story house. He found an earring in the driveway and turned it in to authorities.
But before the earring could be examined, it went missing, authorities said. When interviewed for the “Your Own Backyard” podcast, Lassiter said the earring matched the necklace Smart wears in photos that surfaced after her disappearance.
Even stranger was the beeping that woke Lassiter up one morning.
“It sounded like a digital clock alarm,” he said of the noise coming from the backyard. Months later, the sound stopped.
