Chris Casher, Ronald Darby don't talk

TALLAHASSEE, Fla. --Florida State football players Chris Casher and Ronald Darby refused to testify during a student conduct code hearing regarding allegations that reigning Heisman Trophy winner Jameis Winston sexually assaulted an FSU student nearly two years ago, people familiar with the case said.

Winston, who has guided the Seminoles (No. 4 CFP, No. 3 AP) to a 12-0 record going into Saturday's ACC championship game against Georgia Tech (No. 11 CFP, No. 12 AP) in Charlotte, North Carolina, faces four potential violations of FSU's student conduct code, including two related to sexual misconduct.

Winston was accused by a woman of sexually assaulting her in December 2012. Local authorities declined to press criminal charges.

If found guilty by retired Florida State Supreme Court Chief Justice Major Harding, who is overseeing the conduct hearing, Winston faces potential discipline ranging from a verbal or written reprimand to suspension or expulsion from school.

Winston's attorney, David Cornwell, said Winston is innocent of raping or sexually assaulting the woman and has called her claims "an execution of their extortion plan."

Casher and Darby, who were Winston's roommates at an off-campus apartment and were there on the night of the alleged incident, refused to answer Harding's questions on the advice of their attorneys. Citing a Florida State student conduct rule which allows students to refuse to testify, Casher and Darby told the judge they intended to "stick by their prior position" because of a threatened lawsuit.

In November 2013, Casher and Darby presented signed affidavits to the state attorney's office, in which they said they saw Winston having consensual sex with the woman. Casher later told investigators that he went into Winston's bedroom to videotape their sexual encounter, but destroyed the cell phone before he could give it to police.

Casher and Darby appeared before FSU's student judiciary this past spring for their actions on the night of the alleged incident. Casher was charged with invading the woman's privacy and was placed on one year's probation by the school. Darby was cleared of any wrongdoing.

In April, Tallahassee police attempted to interview Darby and Casher as part of an investigation into whether or not they should be charged with voyeurism. Casher and Darby refused to be interviewed, and the state attorney's office declined to pursue the case.

The student conduct hearing is expected to last one or two days, according to sources familiar with the case, and Harding is required to provide Winston and his accuser with notice of his decision within 10 school days under FSU's rules and procedures.

There were three or four witnesses who testified on Tuesday, according to John Clune, the woman's attorney, and more are scheduled to appear at the hearing on Wednesday. Clune said his client was never in the hearing room at the same time as Winston.

"They were not and that's not going to happen," Clune said. "That's just not something that is a healthy thing for our client."

The woman, who is no longer an FSU student, testified in front of the judge after the opening statements.

"I think for our client it's a very empowering day and it's a very important day," Clune said. "You have the Heisman Trophy winner on trial for rape today. I think seeing where things have come over the past 10 months was kind of an emotional moment for her, and having to recount some of what happened to her was difficult but empowering at the same time."

Clune said his client was relieved the case was finally being heard.

"I think there are so many women that have been victims of athlete violence around the country that have had to deal with their cases being swept under the rug," Clune said. "This certainly at one point seemed to be one of them. So to be at an actual hearing with the possible charges of sexual assault being on the table, it's a big day. It really is."

Winston was ushered to an SUV by Cornwell after the hearing ended for the day shortly before 5 p.m. ET Tuesday. Winston didn't answer questions from reporters. Cornwell said the day "went as they expected," and that, "We think this nightmare will be over very soon."

Clune's partner, Baine Kerr, advised the woman during Tuesday's hearing. Neither Cornwell nor Kerr is permitted to speak on their clients' behalf during the hearing, but they can advise them.

Speaking after the hearing, Seminoles coach Jimbo Fisher addressed Winston's frame of mind and credited him for being able to focus despite the investigation.

"During the day he does that but at night he'll go back and study [film]," Fisher said. "He's an extremely intelligent young man. He can compartmentalize a lot."

Information from ESPN.com's Jared Shanker was used in this report.