SALINAS, Calif. (AP) — The man last seen with Kristin Smart, the college freshman who vanished from a California campus 25 years ago, is on trial more than a year after he was arrested on a murder charge along with his father, who is accused of helping hide her body.

Opening statements began Monday in Monterey County Superior Court in Salinas in the case against Paul Flores and his father, Ruben Flores, who is charged as an accessory. Both men have pleaded not guilty.

Deputy District Attorney Christopher Peuvrelle described how Smart disappeared from California Polytechnic State University over Memorial Day weekend in 1996, the San Luis Obispo Tribune reported.

“In 1995, Stan and Denise Smart sent their oldest daughter Kristin to Cal Poly in San Luis Obispo,” Peuvrelle said in his opening remarks. “During her freshman year they looked forward every Sunday to a phone call from her — it was their ritual.”

That weekend, the call never came, Peuvrelle told jurors.

Smart’s remains have never been found and the mystery of how she vanished from the scenic campus tucked against a verdant coastal mountain range is likely to be central to the trial.

“And while the entire community banded together to search for Kristin desperately, Paul and Ruben Flores did not join in,” Peuvrelle said to the jury. “You will hear Ruben Flores would tear down missing posters of Kristin — tore down her smiling, beautiful face — called her a ‘dirty slut,’ all while her corpse was decomposing underneath his deck.”

Prosecutors maintain the younger Flores, now 45, killed the 19-year-old during an attempted rape May 25, 1996 in his dorm room at Cal Poly, where both were first-year students. His father, now 81, allegedly helped bury the slain student behind his home in the nearby community of Arroyo Grande and later dug up the remains and moved them.

During his opening remarks, defense attorney Robert Sanger told jurors that if Paul Flores and Smart did interact on campus over that weekend, it was brief and no attempted rape occurred.

Paul Flores had long been considered a suspect in the killing, but prosecutors only arrested him and his father in 2021 after the investigation was revived.

San Luis Obispo County Sheriff Ian Parkinson acknowledged missteps by detectives over the years and he credited a popular podcast about Smart’s disappearance called “Your Own Backyard” for helping unearth new information and inspiring witnesses to speak with investigators.

Investigators have conducted dozens of searches over two decades, but turned their attention in the past two years to Ruben Flores’ home about 12 miles (20 kilometers) south of Cal Poly in the community of Arroyo Grande.

Behind lattice work beneath the deck of his large house on a dead end street off Tally Ho Road, archaeologists working for police in March 2021 found a soil disturbance about the size of a casket and the presence of human blood, prosecutors said. The blood was too degraded to extract a DNA sample.

San Luis Obispo Superior Court Judge Craig Van Rooyen ordered the pair to trial after a 22-day preliminary hearing in which he found a “strong suspicion” the father and son committed the crimes they were charged with, that a grave existed under Ruben Flores’ deck and it once held Smart’s remains.

The Tribune reported that Sanger used his remarks to begin to discredit the forensic evidence Peuvrelle had laid out, particularly the claims by the archaeologist who is expected to testify that the stain underneath Ruben Flores’ deck is the result of a body.

Cadaver dogs used in the search are unreliable, Sanger said, and the profession itself is not regulated. He said handlers certify each other, and there is not a government agency that oversees them. He also said handlers are volunteers, not scientists, such as the witness he plans to call.

“I don’t want to demean these volunteers, they are very helpful,” Sanger said. “They specialize in disaster, finding bodies — that’s what they’re good at and bless their hearts they’re out there helping people, but from a forensic science standpoint, you’ll hear that it’s nothing other than a clue.”

Paul Flores was the last person seen with Smart on May 25, 1996 as he walked her home from an off-campus party where she got intoxicated.

He downplayed his interactions with her when he first spoke with police three days later, saying she walked to her dorm under her own power, though other witnesses said that she had passed out earlier in the night and Flores helped hold her up as they walked back to campus.

Flores had a black eye when investigators interviewed him. He told them he got it playing basketball with friends, who denied his account, according to court records. He later changed his story to say he bumped his head while working on his car.

At a preliminary hearing last year, prosecutors presented evidence that four cadaver dogs stopped at Flores’ room and alerted to the scent of death near his bed.

Van Rooyen ruled in favor of a defense request to move the trial out of San Luis Obispo County because it was unlikely the Flores’ could receive a fair trial with so much much notoriety in the city of about 47,000 people.

The case was moved 110 miles (177 kilometers) north to Salinas, a small city in the agricultural region where John Steinbeck set some of his best-known novels.

Sanger previously said the evidence remained the same as it did in the 1990s when Paul Flores was the prime suspect but never charged with a crime.

“The evidence then and now is based on speculation and not proof of facts,” Sanger said in court documents.

Sanger has tried to pin the killing on someone else — noting that Scott Peterson, who was later convicted at a sensational trial of killing his pregnant wife and the fetus she was carrying — was also a Cal Poly student at the time.

Trial Judge Jennifer O’Keefe — who is a year younger than Kristin Smart would be today — however, has barred suggestions of alternate suspects unless Sanger can provide evidence of their direct involvement.

Separate juries were selected to weigh the evidence against each defendant. The trial is expected to last about four months.