ARROYO GRANDE, Calif. (AP) — Scientists specializing in human decomposition and soil took samples from the ground Thursday outside a home connected to the man convicted of killing 19-year-old college student Kristin Smart in 1996. Her body was never found.

The San Luis Obispo County Sheriff’s Office served a search warrant Wednesday on the home of Susan Flores, whose son Paul Flores was convicted in 2022 of killing Smart. Authorities have not answered questions about what prompted the search.

Tim Nelligan, an expert in soil vapor testing, confirmed by phone Thursday that he was on the premises, gathering samples from the yards of Flores and a neighbor. He said is team has, in general, “come up with a methodology to assess soil vapor” and its relation to “human cadaver decomposition,” but that he could not discuss the current investigation.

Smart went missing from California Polytechnic State University in May 1996 after returning from an off-campus party. Prosecutors alleged she was killed during an attempted rape and that the last person she was seen with was Paul Flores, a fellow student. She was declared legally dead in 2002.

The decades-old case has captivated the public, fueled in part by a podcaster who helped investigators by bringing forward additional witnesses. Chris Lambert of the “Your Own Backyard” podcast first reported the search of the home in the central coast town of Arroyo Grande, about 100 miles (160 kilometers) northwest of Los Angeles.

Attempts to reach Susan Flores for comment Wednesday and Thursday were not successful. She has never faced criminal charges related to the case.

Nelligan and other scientists poked instruments into the soil and pulled up long tubing. Soil vapor sampling, which is an evolving science, involves collecting underground gas samples to detect volatile organic compounds associated with human decomposition.

Lambert, the podcaster, said he did not know much about the search, but was optimistic investigators could locate Smart’s body. He said past searches of Susan Flores’ home have never been thorough.

“This property in particular has been overlooked for quite some time,” he said Thursday in front of the house.

Paul Flores and his father, Ruben Flores, were arrested in 2021.

Prosecutors alleged Smart’s remains were buried on Ruben Flores’ property and later moved. He was acquitted of accessory charges. That property is different from the one currently being searched.

Paul Flores was sentenced in March 2023 to prison, where he has been physically attacked at least twice.

In 2024, a judge ruled that Paul Flores must pay just over $350,000 to Smart’s family for costs they incurred after her death.

The family has said it would forgo restitution if Flores would tell them where the woman’s body was. Flores’ attorney, Harold Mesick, said in 2024 that the defense did not know where her remains are. Flores maintains his innocence.

The county district attorney’s office said Wednesday it was helping the sheriff’s office with the investigation.

“While those responsible for Kristin’s death — and those with knowledge of her whereabouts — could provide answers at any time, we remain firmly committed to using every lawful tool available to locate Kristin’s remains and to support her family until she is brought home,” District Attorney Dan Dow said in a statement.