A 2020 search of a trailer seized as part of the Kristin Smart investigation revealed a stain “similar” to a human body after the inside was sprayed with a chemical used to detect bodily fluids, according to testimony Wednesday from the San Luis Obispo County sheriff’s detective who is leading the case.

Detective Clint Cole, who was assigned to the investigation in 2017, testified that the chemical revealed a “suspicious” reaction on the inside of one of the trailer’s doors.

Cole said he used Bluestar, a forensic chemical used to rapidly test the presence of blood. The chemical could also be used to detect cleaning agents, he added.

“There was no Bluestar reaction anywhere else in the trailer, just in that one particular spot,” Cole said.

The trailer was seized on the detective’s belief that it was used in the first week of February 2020, during a clandestine operation to transport Smart's remains from Ruben Flores’ residence in the 700 block of White Court, where prosecutors believe Smart had been buried for more than two decades.

Smart was a 19-year-old Cal Poly freshman who investigators believe was with Paul Flores, Ruben Flores’ son, shortly before she disappeared on May 25, 1996.

Paul Flores was last seen with Smart near the intersection of Perimeter Road and Grand Avenue at about 2 a.m., just steps away from their red brick dorms, after walking back from an off-campus party on Crandall Way, according to witness Cheryl Manzer, who walked with them before splitting off from the pair.

Smart was never seen again. She was declared legally dead in 2002.

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

They were arrested and charged in April, nearly 25 years after Smart’s disappearance. They both have pleaded not guilty.

Cole’s testimony came during Paul and Ruben Flores’ preliminary hearing, which began on Aug. 2. At the conclusion, a judge will determine whether there is probable cause to uphold the charges in order for the case to proceed to trial.

He was one of two witnesses who testified Wednesday, the other being Edward Chadwell, a retired general contractor who built the Flores family home in 1991.

Cole provided testimony about the trailer search while responding to cross-examination by Ruben Flores’ attorney Harold Mesick, who asked how he was able to obtain a warrant for his client’s DNA from a buccal swab on May 19, 2021.

In March and April of 2021, sheriff’s detectives served a search warrant to use ground-penetrating radar on Ruben Flores’ home, where they discovered a 4-foot “anomaly” in the soil located in a spot underneath the deck of the house which contained the presence of human blood and various fibers, including a red fiber, according to Cole.

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Upon questioning by Mesick, Chadwell testified that he used pink mason’s twine during construction of the house.

Additionally, Cole testified that he spoke to a former 10-year tenant of Ruben Flores’, who said he was never allowed to access that portion of the deck area.

After pausing for a brief moment, Cole continued with his testimony, adding that they also served a Volkswagen that he later found was registered to Paul Flores’ sister in May 1996.

Cole said he considered numerous factors, including knowledge of the case, and Paul Flores’ alleged scratches on his knees, a black eye and unaccounted for time between the hours of 5 a.m. and 6 p.m. on May 25, 1996.

“I believe that the family did assist him potentially using one of the vehicles at their disposal,” Cole said. “Paul’s sister lived approximately one mile from campus. He had called her that night on his way to the party.

“The family was together that entire weekend, or most of that weekend, at the residence,” Cole said.

Following Cole’s testimony, Bob Sanger, Paul Flores’ attorney, asked if he met with Deputy District Attorney Christopher Peuvrelle to decide what would be the most damaging testimony to the defense.

Cole said he was only completing his answer to Mesick’s question.

Sanger’s question came following intense testimony with Cole over alleged inappropriate contact with Jennifer Hudson, who testified hearing Paul Flores utter alleged incriminating statements about Smart during the summer of 1996.

In addition, Sanger grilled Cole over inconsistent dates written on his notes from the investigation alleging text messages were deleted from a WhatsApp smartphone application.

Sanger asked if Cole had an inappropriate conversation with Hudson on his cellphone after he had been drinking.

“Did you call her late at night after you had been drinking?” Sanger asked.

“I don’t’ recall,” Cole said. “It’s possible. We could have talked. I have very poor cell reception at my house, so I doubt it.”

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