Where is Kristin Smart? A search warrant was issued on the killer’s mother’s property after the remains were found

Nearly three decades after Kristin Smart disappeared, San Luis Obispo County Sheriff’s investigators on Wednesday served a search warrant at the home of her killer’s mother and prepared to scan and sample the remains of her body.

The Arroyo Grande home belongs to Susan Flores. Her son, Paul Flores, was the last person seen with Smart as the two went to her residence at Cal State San Luis Obispo after a party on Memorial Day weekend in 1996. He was sentenced to 25 years to life in prison three years ago for killing Smart. But his body was never found.

Three years ago, a team of scientists working in the backyard of Susan Flores’ neighbors using soil vapor samples discovered the presence of volatile organic compounds that they said could be associated with decaying human remains.

A sheriff’s investigator served Susan Flores with a search warrant just after 7 a.m., and she is able to access a neighboring home where scientists in 2023 discovered a combination of mutant organisms. The reasons have been explored before. Sources familiar with the investigation said the investigation is expected to last two days.

“The San Luis Obispo County Sheriff’s Office is conducting an additional investigation into the location 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 operation is the result of a search warrant signed by a Superior Court judge. The Sheriff’s Office remains determined to bring Kristin home to them.”

San Luis Obispo County Sheriff Ian Parkinson, along with investigators and radar and ground science experts, showed up at the home Wednesday morning. Sheriff’s officials confirmed that there was a search warrant. The department said it would not comment beyond the statement.

Among those at the scene was Tim Nelligan, a soil engineer who, along with another scientist and an FBI research chemist turned professor, found signs of human remains in the data they collected at the site. Later, the Sheriff’s Department asked for more data and research from the school to support their new method of finding remains using soil vapor.

The team used a technique known as soil vapor sampling, which they say can detect volatile organic compounds associated with decaying human remains. Although the practice is still in the theoretical research stage, scientists have spent two decades studying the chemical compounds involved in the breakdown of the human body.

Previously, the Sheriff’s Department said officials had contacted the FBI regarding 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 were confident in their findings.

Soil vapor sampling

Nelligan, an environmental engineer from San Clemente, met Smart in college. He remembered knocking on his house and asking to use his landline.

“There was this girl who was 6 feet tall, who was attractive on her own, who introduced herself as Roxy,” Nelligan said, referring to the nickname Smart used for her favorite clothing company.

A week and a half later, he said, his disappearance was covered by local TV stations.

Nelligan said she doesn’t know Smart’s family, but she always wished she could help.

Timothy Nelligan goes over findings in the Kristin Smart case in his San Clemente office.

(Christina House/Los Angeles Times)

The public’s interest is there again, no longer and kept Smart’s disappearance from the news from time to time, but a podcast called “Your Yard,” started in 2019 by Chris Lambert, illuminated a new area in the cold case.

In November 2019, he began researching how bodies decompose in soil. Two months later, he hired Steve Hoyt, another Cal Poly grad with a doctorate in environmental science who had built a soil sampling business on the Central Coast. Brian Eckenrode, a retired FBI scientist and human decomposition expert, joined them in 2021.

Authorities had repeatedly searched the grounds of Paul Flores’ parents’ homes. Sheriff’s deputies even used radar and ground-penetrating cadaver dogs to search Ruben Flores’ property in Arroyo Grande in 2021. No remains were found, but a month later, both Flores men were arrested and charged in connection with Smart’s murder.

In 2023, the three entered the Arroyo Grande house of Susan Flores, a short distance from Ruben Flores. The property has been subject to search warrants in the past – including one stemming from civil suits against the Smart family.

Timothy Nelligan believes that a vapor probe, like the one pictured, could help find the remains of Kristin Smart.

(Christina House/Los Angeles Times)

Nelligan contacted neighboring homeowner Marcia Papich, whose fence encloses Susan Flores’ back yard. After digging holes in the dirt near the property line, Nelligan pushed a small instrument known as a soil vapor probe, which has a long straw-like attachment, about three to five feet into the earth. Any gases the probe encountered were vacuumed out and collected, then sealed in a canister. The extracted organic compounds are then sent for analysis to the San Luis Obispo laboratory operated by Hoyt.

What emerged when those compounds were represented by color on a plum map and compared to a number of samples from nearby soil control sites indicated the presence of a decomposer, according to Eckenrode.

Susan Flores has never been charged in connection with her son’s crimes. During the search three years ago, he insisted that he did not kill Smart and that his family did not know the missing student.

Attorney Harold Mesick, who received a not guilty verdict in the charges involving Ruben Flores, told The Times in 2023 that the idea that the body was in Susan Flores’ backyard was “ridiculous.”

He suggested that if the authorities look at Smart’s remains, they should expand their investigation into who really took him, keeping in mind that the Flores family had nothing to do with his disappearance. Mesick stressed that repeated searches of Susan and Ruben Flores’ property turned up nothing, and said authorities did $30,000 in damage to Ruben Flores’ property by digging under his deck — a search that failed to find anything.

Of course, researchers cannot say whose remains may be in Flores’ yard or when they were buried. But the three were confident in 2023 that they would find a body in the ground.

Now the search is back.

An earring found in the driveway of the home of Susan Flores, the mother of convicted felon Paul Flores, reportedly matched the necklace Kristin Smart wore in photos in newspapers and on billboards about her disappearance.

(Don Kelsen/Los Angeles Times)

The Branch Street home came under scrutiny in the months after Smart’s disappearance. Mary Lassiter rented a blue two-story home. He found an earring on the street and handed it over to the authorities.

But before the earring was checked, it was missing, officials said. During an interview on the “Your Own Backyard” podcast, Lassiter said the earring matched the necklace Smart was wearing in photos that surfaced after her disappearance.

Even a stranger was the sound of a voice that woke Lassiter one morning.

“It sounded like a digital alarm clock,” he said of the sound coming from the back of the house. After months, the noise stopped.