Rod Knecht writes in a letter to the editor of the Edmonton Journal that recent media coverage about the woman's experience has been "inaccurate and inflammatory."
Police said they were called to a motel to check on the welfare of an 18-year-old woman in mid-February and that paramedics treated her at the scene.
Knecht writes that officers took her to the police station for followup investigation.
But he says she gave no indication she had been sexually assaulted, so they brought her to the city's Remand Centre because of her warrants.
He says she didn't disclose she had been sexually assaulted until "several hours later" and was taken to hospital and an investigation was started.
"Unsubstantiated and unfounded reports of racism and police ineptitude by third-party observers were reported on in social media, absent the facts of the initial response," Knecht wrote in his letter to the paper.
"These unchecked erroneous views were reported as accurate to a broader audience in the mainstream media. The comments undermined the efforts of first responders who worked to assist the female victim and only served to negatively impact the sexual assault investigation," he added.
The investigation into the sexual assault is ongoing, he says.
Tom Engel, a lawyer who is representing the woman, said his client suffered a memory loss during the incident and that he is still trying to get information from police.
Engel said all the woman remembers is being in a hotel room and then waking up in a cell.
"I think it's fair to say this is a complicated matter," Engel said on Saturday. "At this time, we're saying we don't want to say any more until we know more."
An Edmonton youth worker, Mark Cherrington, who had come to the woman's defence last month, said police essentially ignored the woman's assault complaint, telling her to come back after she was out of jail.
The case prompted outrage on social media websites and a demonstration was held by a small group of protesters near the jail on Friday.
"Clearly police are not going to do their jobs so we need to do it. We need to come up with systems to protect each other," one demonstrator told the crowd.
Knecht wrote in his letter that the officers' actions were "professional and appropriate."
"Sometimes we might be a little too quick to blame the police. In this case, irresponsible and unaccountable social media commentary was adopted as factual, and subsequently sensationalized, in the mainstream," the chief wrote.
Also on HuffPost