Christiansen allegedly made contact with the woman through a telephone dating service and agreed to meet her July 1. He then went to the woman's home, near 5500 W. Sunshade Cove (3450 South), followed her into her bedroom and said he was a police officer, according to charges.
According to search warrant documents filed last month, Christiansen said he was arresting her for prostitution and cuffed her hands behind her back. Christiansen said he would let her go in exchange for sex, according to the search warrant.
The woman told West Valley City police that Christiansen forced her to perform oral sex, ripped off her shirt and grabbed her "roughly" before having sex with her, investigators wrote.
Christiansen allegedly left a condom in her toilet but forgot to flush, according to the search warrant affidavit.
The woman said that when Christiansen left, he took $50.
The woman said she had asked to see Christiansen's badge, but he refused. Police say he is not employed by any law enforcement agency.
As part of a police investigation, the woman telephoned Christiansen again and told him in a recorded call that she didn't believe he was a police officer. Christiansen allegedly told the victim that he was an officer, but he refused to identify his department and threatened that officers would arrest her for prostitution if she were to try to report him.
A neighbor reported seeing a motorcycle that looked like an old police motorcycle at the time of the alleged rape. Officers pinged Christiansen's cell phone to an address near 2700 West and 4700 South, where they found a motorcycle matching the neighbor's description, according to police. The license plate showed the bike was registered to Christiansen, and his driver's license photo matched a photo he had sent to the victim's cell phone before she agreed to meet him, police wrote.
However, when officers tried to serve a search warrant to collect DNA evidence, they learned that Christiansen was in Denver, according to search warrant documents. He had not been booked as of Thursday evening.
Christiansen is described in the search warrant as 5-foot-11, with green eyes, brown hair and several neck tattoos.