The letter states that the student is approximately 40 years younger than Roberts.
"You have engaged in egregiously unprofessional conduct resulting from your position… " James D. Morales, USU's vice president for student services wrote in the letter. "You have placed yourself and the university in grave risk of embarrassment and legal responsibility and are therefore dismissed without further notice."
The alleged incident at Roberts' home occurred in August, but was not reported to Logan police until Sept. 5 by the student's sister, who had been told about the alleged incident by another woman, according to a Logan City police report.
The alleged victim told investigators she was invited to Roberts' home, where he showed off memorabilia from his professional basketball career and expressed his desire to see her naked and have sex, according to the police report.
The woman said she attempted to rebuff Roberts by telling him that she is a lesbian, but he persisted with physical contact, the report states.
"I felt trapped," the woman told police. "I looked up at him… I was terrified … I couldn't leave because my feet were frozen."
The report says the woman engaged in sex acts with Roberts, who told her they would "both get in big trouble for this" and could lose their respective jobs.
In an interview with police, Roberts told officers his relationship with the alleged victim was consensual and that he had halted intercourse out of respect for the woman's sexual preferences.
Roberts' attorney, Cara Tangaro, said he has maintained his innocence. Roberts has cooperated with police and provided them with copies of texts and e-mail messages he exchanged with the alleged victim. The two also met socially on several occasions after the alleged incident occurred, she said.
"There was no rape, there was no sexual assault," Tangaro said Thursday. "I think it was more of what I would refer to as buyer's remorse."
Tangaro said she believes the university was hasty in its decision to fire Roberts, but that he has no plans to pursue a wrongful termination lawsuit.
"I think they were acting out of an over abundance of caution," she said of USU officials. "Universities are so worried about being in the limelight that I think in this case, they over-compensated."
Police turned the case over to the Cache County Attorney's Office, which declined to file charges, citing insufficient evidence, according to a Thursday article in the USU student newspaper, The Statesman.
A telephone message left for prosecutors was not immediately returned Thursday.
A USU alum and former star basketball player who played in both the American Basketball Association and the National Basketball Association, Roberts was hired by the university in May 2013.
In his capacity as assistant vice president of student engagement and diversity, Roberts served as advocate for minority students, focusing on student retention and success.
USU officials initially placed Roberts on administrative leave pending investigations by police, the office of student services and the university's Title IX coordinator, who considers allegations of unlawful sexual assault or harassment.
According to the letter, those investigations appear to have been incomplete at the time of Robert's Sept. 18 firing.
But Morales said he believed the university had sufficient grounds for termination based on his own investigation and Roberts' admission that the alleged offense was worthy of costing him his job.
Per university policy, Roberts was paid two weeks severance.
The Tribune generally does not name alleged victims of sexual assault.