The Indiana Utility Regulatory Commission said it will review four years of cases regarding Duke Energy Corp.’s expensive Edwardsport coal-gasification plant amid a growing ethics controversy involving the company and state regulators.

The commission has also summoned Jim Rogers, the CEO of North Carolina-based Duke, to justify anew the need for the Edwardsport plant, during a hearing on Nov. 3.

In addition, the State Ethics Commission on Thursday filed formal charges against Scott Storms, the IURC former top attorney, for negotiating a job with Duke even as he participated in decisions regarding Duke and its Edwardsport plant. That behavior violates state conflict-of-interest statutes, the complaint alleges.

The Ethics Commission had initially OK’d attorney Storms’ September switchover to work at Duke.

Storms’ contact with Duke officials emerged in e-mails discovered in a probe by Gov. Mitch Daniels’ office, according to Duke. Daniels fired former IURC Commissioner David Hardy on Oct. 5 over the matter and Duke placed its Indiana CEO on administrative leave.

Now, the IURC has opened up its own investigation into the ethics flap, the commission announced Thursday.

Duke’s Edwardsport plant has been controversial as the costs for building it have climbed to $2.9 billion from initial estimates near $1.5 billion. In July, Storms signed off on Duke’s request to pass those costs on to customers.

The Edwardsport plant is already about 70 percent complete, and Duke recently reached a settlement with consumer groups to cap the plants costs at $2.975 billion. Those costs, when passed on to Duke customers, would raise their bills by about 16 percent between now and 2013.