A man accused of raping a woman on a camping trip last year pleaded not guilty to a felony charge Wednesday morning in Natrona County District Court.

Robert I. Miller, Jr., 21, is charged with one count of first-degree sexual assault. He could face five to 50 years in prison and a $10,000 fine if convicted.

Charging papers allege Miller was on a camping trip with the victim and her family 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 told Miller "no" and "stop" on both nights, 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.

Miller remains in custody on $50,000 cash or surety bond. His trial is set for July 31.