A group of elected officials investigating Louisville’s high gas prices are intensifying their focus on wholesalers.Attorney General Jack Conway, Governor Steve Beshear, Congressman John Yarmuth and Louisville Mayor Jerry Abramson launched their investigation six weeks ago. So far, they’ve ruled out Louisville’s use of reformulated gas and retailer collusion as possible causes of the higher prices. They say retailers across the state earn the roughly the same amount from gas, and other cities using RFG have lower prices than Louisville.Conway announced Friday that he has issued subpoenas to Kentucky fuel wholesalers. He’s also asking the Federal Trade Commission to investigate the 1997 merger of Marathon and Ashland Oil.Yarmuth blames the merger for creating a monopoly and driving prices up.“With one company providing 90% of the fuel for our community, up to 90% of the fuel, and a lack of regulation from Washington, this was predictable," he said.The group expects to have more information in 45 days, at which point they may pursue legal action against Kentucky fuel wholesalers.