ANCHORAGE—Anchorage police Chief Mark Mew said at a City Hall news conference Wednesday that former police officer and now convicted serial rapist Anthony Rollins was a “sociopathic anomaly” in the department.

Mew also said APD knew about Rollins' sexual misconduct at least six years before he was suspended and taken off the streets.

Mew began by reading from a prepared statement, expressing “regret” to Rollins' victims, “the most tragic victims in this sad tale.” He also said Rollins' actions have “diminished the public trust that his peers have worked so hard to build and the rest of us so jealously protected.”

When CBS 11 News asked Mew when APD knew Rollins was having sex on duty, Mew said, “I can't give you a specific date, but it was in the mid-2000's. I wasn't here at the time, so maybe there are others, we have investigators and prosecutors here who can maybe put a better date on it than I could.”

When CBS 11 News asked those investigators and prosecutors about the history of sex-on-duty complaints against Rollins, they refused to comment on what they called APD Internal Affairs investigations, which Mew said are sealed except under court order.

“There was a previous allegation that was also investigated,” Mew said. “We couldn't make a criminal case out of that and he was disciplined for that. It's a personnel matter and they wont let me tell you (how he was disciplined) but I'll tell you it was severe.”

When pressed for clarification, Mew said it was “about 2003” when the first complaint against Rollins was investigated by Internal Affairs. He stressed, however, that the complaint was about consensual sex on duty; not criminal. The criminal investigation began in April 2009, when Rollins was immediately suspended.

All police sources insist that, until April 2009, all the complaints APD had gotten about Rollins having sex on duty was consensual, not criminal.

“This pattern of conduct was going on before we got the complaint that opened up the investigation, but once we got that complaint I think we pulled out all the stops,” Mew said.

CBS 11 News pointed out that the global positioning system tracking device was placed on Rollins' police car in August of 2008 but it wasn't until nearly nine months later that he was pulled off duty. We asked: If APD had been tracking Rollins via GPS, why not act sooner—before he sexually assaulted five women?

“We were already building the case on the previous women,” Mew said. “Certainly if we were aware if a crime was about to be committed we would interrupt it.”

As for Rollins' claim during the trial that other officers also have sex on duty, Mew said, “I'll tell you that, very rarely, this has occurred, over the last, off and on, 30 years that I can think of, a few times. There have been employees who have had consensual sex with each other while on duty. These people have been disciplined. There have been a few employees who have had on-duty consensual sex with members of the public. The few who didn't lose their jobs outright were punished severely.”