Paul Flores and Father Ruben on Trial

On Memorial Day weekend in 1996, college freshman Kristin Smart headed to an off-campus party at California Polytechnic State University in San Luis Obispo — and mysteriously vanished on her way home.

The 19-year-old was never found, but suspicion immediately began swirling around Paul Flores, a fellow freshman who was allegedly the last person seen with her, and later, his father, Ruben Flores, who authorities believe helped his son hide her remains.

Now, 26 years later, her still-heartbroken family may finally see justice served.

On Monday, a murder trial in connection with Smart's presumed death began in Monterey County Superior Court in Salinas, where prosecutors will work to prove their belief that Flores, now 45, raped and killed the promising college student and that his father, now 80, helped hide her body.

The trial was supposed to take place in San Luis Obispo County, where the alleged crime took place, but a judge ruled in favor of a request to move to another county to guarantee that Paul and Ruben would receive a fair trial, The Tribune of San Luis Obispo reports.

After a lengthy investigation with lots of twists and turns, in April 2021, Paul and Ruben were arrested and charged in connection with Smart's presumed death and disappearance.

Paul was charged with first-degree murder. Ruben was charged with accessory after the fact to the crime of murder after he was accused of burying Smart's body in his yard before moving it, prosecutors have said.

Both pleaded not guilty and will be tried at the same time, but with different juries who will rotate in and out of the courtroom, Court TV reports.

Even though prosecutors still do not know where Smart's body is, they are confident the evidence they have gathered over the years allegedly shows that Paul did, in fact, murder Smart.

Since 2011, according to the San Luis Obispo County Sheriff's Office, investigators have collected more than 140 "new items of evidence," searched nine separate locations, served 18 search warrants, resubmitted 37 pieces of evidence from the investigation's early stages for more-current DNA testing and conducted 91 face-to-face interviews, The Tribune reported.

Four cadaver dogs alerted authorities to the scent of a dead body near the bed in Paul's dorm room, prosecutors said in a preliminary hearing in 2021, the Associated Press and CBS Sacramento reported.

Paul also sported a black eye when he was questioned by police after Smart's disappearance, which he said he got playing basketball and later, from bumping his head, the AP reports.

Paul allegedly tried to rape Smart in his dorm room before killing her, San Luis Obispo County District Attorney Dan Dow said in 2021.

"We certainly believe Mr. Flores' dorm room was a crime scene," he said.

Defense: Evidence 'Based on Speculation'

Defense attorney Robert Sanger says the prosecution has a weak case.

"The evidence then and now is based on speculation and not proof of facts," Sanger said previously in court documents, the AP reports.

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Ruben's attorney, Harold Mesick, had said previously that authorities have scant evidence that his client buried a body in his backyard in Arroyo Grande, even though authorities say they found "biological evidence" there, the AP reports.

"It was a hot mess because it's been previously excavated," Mesick said, the AP reports. "If we even call it evidence, it is so minimal as to shock the conscience."

When reached by PEOPLE, Mesick said his client "is 100 percent innocent," noting that he was unable to comment further because the trial was underway.

Paul's attorney did not immediately respond to PEOPLE's requests for comment.

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