A Casper man who was previously sentenced to a term of probation for possessing child pornography now faces prison time after admitting to sexually assaulting a woman during a camping trip last year.

Robert I. Miller, 22, pleaded guilty Wednesday in Natrona County District Court to one count of second-degree sexual assault. The charge was originally filed under the first-degree statute.

The second-degree charge to which Miller pleaded guilty carries a two- to 20-year prison sentence. Under the plea agreement, however, prosecutors will argue Miller spend no more than seven years in prison.

According to court documents, Miller accompanied the victim and her family on a camping trip at Pathfinder Reservoir from May 18-23, 2016 and forced her to have sex on two consecutive nights.

The victim told an investigator that she repeatedly said "no" and "stop," but "Miller continued... against her wishes," the affidavit says.

On the second night, after telling Miller to stop repeatedly, the victim began to cry loudly due to the pain, court documents say. Miller allegedly "pushed her head down into the bedding and continued, even covering her mouth at one point."

Miller reportedly stopped out of fear that the victim's family, who were in their own tents nearby, would hear her crying.

The victim reported the alleged assaults in March, nearly 10 months after the camping trip. The investigator writes in his affidavit that the victim "was upfront [sic] during the interview and said that Miller and she have had consensual sex since November of 2015."

In this instance though, she alleged Miller was demanding a form of sex she did not want to engage in.

In his first interview with authorities, Miller denied assaulting the victim during the camping trip.

However, he agreed to take a polygraph exam. When specifically asked about the alleged sexual assault, Miller "failed that portion of the exam," the affidavit says.

"[Miller's] indication of deception was very high, which indicated... [Miller] was not telling the truth," the affidavit continues.

The investigator interviewed Miller a second time after the polygraph test. In that interview, Miller allegedly admitted to sexually assaulting the victim and reportedly said the victim told him "no" and "stop" throughout the alleged assaults.

Shortly after that camping trip, Miller was sentenced to five years of probation with an underlying prison sentence of up to three years as a result of his guilty plea to one count of sexual exploitation of children by way of possession of child pornography.

Miller remains in custody on $50,000 cash or surety bond pending sentencing.