An Idaho teenager, aged 17, has been formally charged with rape following an investigation that began after the incident was reported by her step-grandfather.

According to EastIdahoNews.com, Zaiden C. Evans could face a life sentence if convicted.

The investigation by the Bonneville County Sheriff’s Office was initiated on April 9 when the step-grandfather informed authorities that Evans and another 16-year-old boy had allegedly assaulted the girl.

During questioning, the girl revealed that she had secretly left her house to meet the 16-year-old, who along with Evans, picked her up.

They took her to the 16-year-old’s residence, which is a camper located next to the step-grandfather’s property. The girl recounted that while they were “hanging out,” she engaged in consensual sex with the 16-year-old. Afterward, she alleged that Evans assaulted her.

Court documents say she repeatedly asked him to stop but he refused, and her efforts to fight him off were unsuccessful.

After Evans raped the girl, the two boys took her back to her step-grandfather’s home.

Apparently, the girl told her mother, who was in California at the time, and she told the step-grandfather.

Deputies collected the clothes the girl was wearing at the time and set up a rape examination and an interview with the girl.

Months later, on September 17, a deputy followed up on the rape examination and told the girl it had found two male DNA profiles on her body. A week later, deputies obtained and executed a warrant for DNA swabs of Evans. The DNA report came back in November, showing that Evans’ DNA was found on the girl’s body.

It’s not clear why deputies took so long to obtain Evans’ DNA, or why it took them two more months after the report came back to file charges.

Evans will be tried as an adult. It’s not clear if the 16-year-old has been charged. Evans has been charged with raping a victim not capable of giving consent — at 13, the girl cannot give consent.

Evans is scheduled for a preliminary hearing on January 28.