(CBS/AP)-- A U.S. Naval Academy midshipman accused of sexually assaulting a fellow student initially told a Navy investigator that he hadn't interacted with her at a party, but he changed his story in a later interview to say he had sex with her, the investigator testified Sunday.
Special Agent Jesus Torres, the Naval Criminal Investigative Service agent who interviewed Tre'vas Bush, said Bush first told him in August 2012 that he did not have sex with the woman at an April 2012 toga party in an off-campus home in Annapolis, Md. But Torres had an interview with Bush in September after the investigator saw a suggestive social media posting by Bush.
Bush then told the agent he had sex with her at the party, Torres testified.
Torres was testifying Sunday night at a military court hearing to determine whether three midshipmen will face a court-martial on charges of sexually assaulting or abusing the woman at the party.
Also on Sunday, defense attorneys finished lengthy cross-examination of the woman at the center of the case.
She testified that Midshipman Josh Tate, one of the men charged in the case, told her shortly the party that the two had sex after she had been drinking heavily. She says that during a subsequent phone call he said he'd only been kidding about having sex with her.
Tate, 21; Eric Graham, 21; and Bush, 22, are accused of sexually assaulting the woman at an alcohol-fueled off-campus party.
The woman has testified that she has no memory of having sex with any of the three men, but later was told by Tate that the two had sex. She said he also told her she had a sexual encounter with Graham.
She has said she only learned of what happened after hearing gossip that she had slept with multiple partners at the party. That prompted her to ask Tate whether they had sex that night. She testified that Tate responded that they had sex and joked that perhaps he should refresh her memory.
The end of cross-examination came a day after the woman was excused from testifying on Saturday. She said she was fatigued from her testimony, which began Tuesday.
Her attorney, Susan Burke, told the presiding investigative officer that one of Graham's lawyers approached her Friday evening and asked whether her client would withdraw from further testimony.
The woman had asked to be excused on both Thursday and Friday due to fatigue from difficult and sometimes graphic questioning by defense lawyers.
"It led me to believe this had been an intentional effort to exhaust the witness," Burke said Sunday.
Ronald Herrington, a lawyer for Graham, said he approached Burke only to ask if the woman planned to continue testifying.
"She choose to disclose her version of the conversation," Herrington said in an interview. "I dispute her version."
Bush and Tate are charged with aggravated sexual assault. Graham is charged with abusive sexual contact.
A hearing to determine whether the three men will face a court-martial began Tuesday at the Washington Navy Yard.
Earlier Sunday, attorneys for Bush and Graham said requests to separate the cases from a joint hearing had been denied by academy officials.