The state's investigation into vote irregularities in Waukesha County will stretch back at least five years, the head of the Government Accountability Board said Thursday.

Questions over vote totals in Waukesha have lingered over the past week after County Clerk Kathy Nickolaus announced she failed to report more than 14,000 votes from the city of Brookfield in initial vote totals.

The new total gave incumbent Supreme Court Justice David Prosser a lead of about 7,000 votes over challenger JoAnne Kloppenburg in the hotly contested state Supreme Court race. Official results in that race have not yet been announced.

Now questions have emerged over Nickolaus' published vote counts from as far back as the fall of 2006, when there were key statewide elections including races for governor and attorney general.

"This is part of what we're looking into. We have a lot of complaints," said Kevin Kennedy, the director and general counsel for GAB. "It's part of our investigation."

Kennedy said the board's current priority is determining the integrity of numbers reported in this spring's election but added investigators are reviewing broader questions about Nickolaus and vote counting.