Alvey told WLKY that the victim went to Hillview police officers to report she'd been raped by an officer in another Bullitt County department. Detectives interviewed the woman about the allegations.
"(Nissen) agreed to take her home, and the allegation is that when he left the police department, he actually drove her to the home of the alleged perpetrator," Alvey told the news station.
From there, Nissen and the other officer, whose name has not been made public, took the woman to Wal-Mart, where they pooled their money to buy her a phone, Alvey told The Pioneer News, Bullitt County's community newspaper.
Nissen is accused of then taking the woman to a hotel and paying for a room, at which point he demanded oral sex from her, the newspaper reported. He also told the woman it was time for her to move to another jurisdiction, Alvey said.
The prosecutor said evidence indicated that the woman was under the influence of drugs or alcohol at the time of the incident.
The theft by deception charge, which is a Class D felony in Kentucky, stems from the fact that Nissen was on duty at the time of the alleged sexual assault, the News reported. Tampering with a witness is also a Class D felony.
Each crime is punishable by up to five years in prison and up to $10,000 in fines.
Official misconduct is a misdemeanor punishable by up to 90 days in jail.
Nissen, a veteran of more than 20 years on the force, made the pages of People magazine in July 2015 after he consoled a female driver who called 911 for assistance after she learned as she drove about the death of her sister.
"Out of safety, I asked if I could talk with her and see if I could get her cooled down a bit," Nissen told People at the time. "I turned the air vents toward her -- it was over 90 degrees that day -- held her hand, and she cried on my shoulder. I had her take sips of water."
Nissen, who was training another officer that day, spent more than an hour with the woman, whose family reached out to thank him on the Hillview Police Department's Facebook page.
Mahoney said in his statement about Nissen's indictment that the detective has been suspended pending the outcome of the case. He also asked the community for patience during the judicial process, as well as throughout the internal investigation that is underway.
"The Hillview Police Department and our officers have worked incredibly hard to be an agency that people of this community can look up to," Mahoney wrote. "We hold our officers to a very high standard and hold them accountable for their actions.
“If the allegations against Detective Nissen are found to be true, you can be assured that we will handle the matter appropriately. The alleged behavior is most definitely not in line with the values of our agency.”