NEW YORK, April 16 (Reuters) - Tarnished executive Thomas Kivisto, who founded oil storage and transport company SemGroup LP [SEMGP.UL], and built it into the 14th largest U.S. private company, now finds himself under scrutiny.

In a report by former FBI director Louis Freeh, Kivisto, a one-time "Tulsan of the Year" whose alma mater renamed its football field after him, could face claims of negligence, fraud and corporate waste after risky bets in the energy market.

A former University of Kansas basketball star, Kivisto started the company in Tulsa, Oklahoma after spending more than a decade at Koch Industries, and paid himself tens of millions of dollars in a company where employees received bonuses twice a year.

Kivisto has not been charged with any criminal activities, but creditors have sued Kivisto, seeking more than $362 million. [ID:nN16260019]

John Tucker, Kivisto's lawyer in Tulsa, told Reuters on Wednesday that many parts of the report "should be taken with a grain of salt." The company said on March 12 it hopes to exit bankruptcy later this year.

Kivisto paid himself more than $46 million in bonuses from 2005 through 2007, according to Freeh's report, which was filed with a U.S. bankruptcy court late on Wednesday.

He and two other top executives also racked up expenses of $2.2 million in the year before the company filed for bankruptcy, including tickets Houston sports events and a private plane.

SemGroup also footed the bill for Kivisto's personal projects, such as a restaurant business and art gallery run by Anna Hollinger, with whom he had a close personal relationship, the report said. Kivisto's lawyer has denied he charged the company for the artwork.

Echoing Barings Bank's Nick Leeson or Enron Corp's Jeff Skilling before him, Kivisto's transformation from business genius to outcast came quickly after a risky, bet-the-company strategy came apart.