COLUMBUS, Ohio -- The woman who accused Dallas Cowboys running back and former Ohio State star Ezekiel Elliott of assaulting her is taking the case to the prosecutor's office and an investigation into the incident is underway.

Columbus police referred the case to the Columbus City Attorney's office due to "conflicting statements" given by Elliott, the woman and witnesses after he was accused of assaulting her in a parked car early Friday morning. According to the director of the prosecution resources unit, Robert Tobias, the city attorney's office is now gathering evidence as the woman, identified as Tiffany Thompson, is pursuing criminal charges.

"At this time, there is an open investigation," Tobias said in an email to ESPN.com. "We are attempting to gather as much evidence as possible."

There is no timetable for concluding the investigation. Elliott is expected to be on the field with the Cowboys when they open training camp Saturday in Oxnard, California.

Elliott, who turned 21 on Friday, denied assaulting the woman and told police that he never lived with her. He has not been arrested or charged with a crime.

Thompson told police that Elliott assaulted her while they sat in a parked car early Friday morning, according to one police report. She told police that she had pain in her right wrist and a red mark but declined medical treatment, according to the report.

Four witnesses, including one who was sitting in the car at the time of the alleged incident, told police that they did not observe an assault.

Thompson also accused Elliott of striking her "several times" and "leaving bruises on her arms" over a five-day period from Saturday to Wednesday, according to a second police report. Elliott, however, told police that he never touched Thompson in "a harmful manner," saying she suffered the bruises during a bar fight.

Thompson told police that she lived with Elliott for about three months, but the running back said that he only paid for her rent and co-signed on her vehicle. Elliott's father, Stacy Elliott, released a statement Friday afternoon, saying his son "has done nothing wrong." "The reported allegations and Internet postings regarding our son are completely false," Stacy Elliott said. "Ezekiel has done nothing wrong. The police have investigated this matter and eyewitnesses have verified the lack of any wrongdoing. The actual evidence in this matter clearly indicates what the real motivation was behind the police being called. We are confident that when the truth comes to light it will reveal the falsity of these claims. Ezekiel has been fully cooperative with the police and will continue to do so -- along with cooperating with the NFL -- moving forward."

ESPN typically does not release the names of alleged domestic violence victims, but Thompson, 20, posted Instagram photos Friday showing bruises on her body. One of her posts was tagged to Ezekiel Elliott.

Thompson's Instagram account was made private later Friday morning.

Dallas coach Jason Garrett confirmed he has spoken with Elliott, the Cowboys' first-round draft pick in April, since the police report was obtained.

"I don't want to comment too much on that," Garrett said Tuesday from a coaches clinic at AT&T Stadium. "We believe we know all about Ezekiel Elliott and what he's all about as a person, and I think it would be premature to make any comment beyond that."

The NFL is reviewing the case under its personal conduct policy. Elliot does not need to be charged with a crime to be penalized by the league.