Topeka ? Westar Energy, the largest electric utility in Kansas, is under investigation by a federal grand jury, according to documents filed by the company.

Federal authorities have subpoenaed documents and testimony concerning use of aircraft leased to Westar, chief executive officer David Wittig, and general company records, according to a filing by Westar with the Securities and Exchange Commission.

In the filing, Westar said the company will cooperate with the U.S. Attorney’s Office in Topeka on the matter. Calls to the company were not returned.

Westar’s board has appointed a special committee to investigate “certain matters relating to the grand jury investigation.”

That board includes Frank Becker of Lawrence, Charles Chandler IV, and John Nettels Jr.

Westar is the parent company of KPL, which provides electric service to northeast Kansas, including Lawrence.

For more on this story, pick up a copy of Saturday’s Lawrence Journal-World.