Duke Energy Corporation CEO Jim Rogers is expected to testify before the North Carolina Utilities Commission at 2 p.m. Tuesday and, under oath, face questions from commissioners who approved Duke Energy's merger with Progress Energy while believing Progress's CEO, Bill Johnson, would head the new company.

Instead, after the approval, Johnson resigned and Rogers took leadership, shocking regulators, shareholders, and the state's consumer advocate, the North Carolina Utilities Commission Public Staff.

A list from commissioners of potential topics of questions includes "the timing of decision regarding replacement" and "reasons for replacement."

"We've never had this happen before," Public Staff Executive Director Robert Gruber said. "It's new ground for all of us."

Commissioners are expected to ask whether the CEO switch was in the works before they gave the merger final approval and whether Duke Energy and Progress Energy withheld any information.

A Charlotte energy attorney who declined to appear on camera because of his work with one of the companies involved said it's extremely unlikely the commission would rescind its approval of the merger, adding that it would be difficult to "unwind" the two companies at this point.

However, both he and Gruber said the newly combined company could face new conditions on the merger and even financial penalties.

Gruber said if this causes Duke Energy to lose credibility with the commission, it could help customers when the company files for a rate increase later this year.

The commission could end up granting a lower increase than requested or setting a lower rate of return for investors.

"It certainly impacts, could impact the way the company deals with the commission and the level of trust going forward," Gruber said.

He said if Duke Energy is fined or any new conditions are imposed, his staff will work to ensure customers aren't negatively affected.