LOS ANGELES >> A former California college student charged with murder in the 1996 disappearance of classmate Kristin Smart pleaded not guilty today and his father denied helping to hide the young woman’s body.

Paul Flores, 44, was charged with first-degree murder in the killing that authorities said happened as he tried to rape Smart in his dorm room at California Polytechnic State University campus in San Luis Obispo after an off-campus party. Witnesses said Smart was intoxicated and Flores had said he would walk her home.

Ruben Flores, 80, pleaded not guilty to a charge that he was an accessory after murder.

Paul Flores was held without bail, but the judge said he would release his father on bail he could afford, which will be determined at a later hearing in San Luis Obispo County Superior Court. The city is 160 miles northwest of Los Angeles.

The arrests last week followed significant developments in the case in recent years as new witnesses came forward, investigators monitored Paul Flores’ cellphone and text messages, and searches were conducted at separate homes where Flores, his father, mother and sister live.

A search at Ruben Flores’ home 13 miles south of campus in Arroyo Grande using ground-penetrating radar and cadaver dogs discovered evidence connected to Smart’s death, authorities said. They didn’t revealed what was found but were seen digging in the backyard April 13 following the arrests.

Defense lawyers, however, questioned the value of the evidence disclosed to them so far in the case.

“The evidence is so minimal as to shock the conscience,” said attorney Harold Mesick, who represents Ruben Flores.

Prosecutor Christopher Peuvrelle countered that investigators had found substantial new evidence since a series of searches last year that ultimately led to the arrests.

“Counsel said, ‘There was very little new evidence,’” Peuvrelle said, referring to Paul Flores’ lawyer, Robert Singer. “Well then he must not have read the same warrant that I have. There is substantial new evidence.”