Washington ? An aide for Rep. Sam Graves said the Missouri Republican was unsure why he had received a $1,000 donation from a former Westar Energy Inc. executive.

The Topeka-based energy company and its executives contributed a total of $56,500 to the campaigns of several House Republicans, including energy subcommittee chairman Joe Barton of Texas, House Energy and Commerce Committee chairman Billy Tauzin of Louisiana, and House Majority Leader Tom DeLay of Texas.

Rep. John Conyers, D-Michigan, has requested an investigation into the donations, which internal Westar documents claim were intended to help secure legislation that could have saved the company billions of dollars. The provision never passed.

“We don’t know why we were included on the internal memo,” Graves spokesman Brian McKenna said. “We were identified that year in a competitive seat, and this was a common list that was circulated in Washington for fund-raising purposes. We can only speculate that was the reason.”

Graves received a $1,000 check from former Westar chief executive David Wittig last June.

An investigation commissioned by Westar’s board of directors alleged Wittig may have coerced Westar employees to make contributions to certain political candidates. However, the report said it did not find “any explicit threats or overt coercive action” by Wittig.

Wittig resigned from Westar in November to defend himself against bank fraud charges unrelated to Westar. He has pleaded not guilty.

Last fall, Barton sponsored an amendment to exempt Westar from a Securities and Exchange Commission regulation requiring oversight when a company splits its interests into separate parts. Westar, which also has interests in natural gas and burglar alarms, could have saved billions of dollars under the exemption.

McKenna said Graves supported the amendment at the time because he “supports the economic development of the region. If it’s good for eastern Kansas, it’s good for western Missouri.”

After a federal investigation into Westar began, Graves and Barton dropped their support and the exemption died.

Samantha Jordan, a spokeswoman for Barton, said there was no connection between Barton’s support for Westar’s regulatory provision and its political donations.