Ed Garland told The Associated Press that officials withdrew the request a week ago, but declined comment on why.
"It is clear that they are doing a careful, thorough and extensive investigation," said Garland, who hoped the investigation would wrap up within a month.
Police are looking into the claim that Roethlisberger sexually assaulted the woman early March 5 at the club in Milledgeville. Roethlisberger has not been charged, and Garland has disputed the claim and has hired his own team to investigate.
It's the second time in a year the two-time Super Bowl champion has been accused of sexual misconduct. This case comes as he faces a lawsuit filed in July by a woman who says he raped her in 2008 at a Lake Tahoe hotel and casino, an allegation he strongly denies. Roethlisberger has not been criminally charged in either case and has claimed counter-damages in the lawsuit.
ESPN first reported that GBI had withdrawn its DNA request.
GBI spokesman John Bankhead did not immediately return a call from The Associated Press.
Roethlisberger, who owns a home about 30 miles north of Milledgeville on Lake Oconee, was at the club and other spots around the college town.
NFL commissioner Roger Goodell said Monday he planned to meet with Roethlisberger about the star's off-field problems. The quarterback's legal team said they wouldn't object to the meeting.
Steelers President Art Rooney II has said the team is concerned and closely monitoring the Milledgeville situation.
Coach Mike Tomlin expressed his concern for his star quarterback Tuesday, characterizing him as a friend he talks to daily "about football, about personal life; that's the nature of our relationship."
"We've been pretty clear from (Steelers president) Art Rooney on down how we are approaching this," Tomlin added at NFL meetings in Orlando, Fla. "At this point, as the investigation runs its course, we'll have comments at the appropriate time."