The two-time Super Bowl champ's lawyer, Ed Garland, said he has hired his own investigative team.
"Any lawyer representing anyone needs to know all the facts so that he can perform his duties," he said.
Roethlisberger has not been charged, and Garland said "no criminal conduct took place."
Carl Cansino, a lawyer for the club where the woman says the assault took place, said he was contacted Friday by the private investigator, Charles Mittelstadt. Cansino was also on hand when authorities interviewed club manager Rocky Duncan Wednesday.
Police Chief Woodrow Blue said at a Monday news conference that investigators expected to speak to Roethlisberger this week. He said Friday that the investigation continues at a steady pace but declined to comment on any details, including whether authorities had interviewed Roethlisberger or asked him for a DNA sample.
"We haven't set any kind of timetable," he said. "Where the investigation leads us will determine that."
The Georgia Bureau of Investigation is also working on the case, but agent Tom Davis in Milledgeville did not return calls seeking comment. Agency spokesman John Bankhead said only that the investigation is ongoing.
Lawyers for the woman who accused Roethlisberger released a statement earlier in the week saying their client is cooperating with authorities and asking the media to respect her privacy. They have not responded to calls and e-mails from The Associated Press seeking additional comment.
Photos have also surfaced online of Roethlisberger smiling alongside the officer who wrote the initial incident report early on March 5. The police chief said the photos were taken hours before the allegation was made.
Blue said Friday he wasn't concerned about the photos, saying the officer, Sgt. Jerry Blash, and others had seen Roethlisberger earlier in the evening. Beyond filing the report, Blash has not been involved in the investigation, Blue said.