Louis J. Freeh, an ex-FBI director whose investigation firm was hired to look into what went wrong at the Tulsa-based energy business, partially blamed SemGroup co-founder Tom Kivisto for the company’s collapse. Among other allegations in his April 15 report, Freeh said Kivisto’s trading strategies were risky and put the company in peril.

On Monday, Kivisto’s attorney, John Tucker, contended the collapse was caused by the loss of bank credit, not unsound trading by Kivisto.

In a written document, Tucker alleged that Freeh’s report was “not an unbiased and balanced assessment of events underlying SemGroup’s bankruptcy, but rather appears to be a targeted response to lay blame on SemGroup’s former officers.”

Freeh responded to Tucker’s statement via an e-mail to the Tulsa World from his counsel, Morrison & Foerster LLP.

“While it is interesting to read what amounts to Mr. Kivisto’s lawyers’ ‘letter to the editor,’ I would have preferred to have Mr. Kivisto’s testimony under oath, which he and his counsel declined to provide. Their press release is inaccurate and misleading on the whole, and it fails to address the central findings of the final report,” Freeh said in the e-mail.

Representatives for Morrison & Foerster declined Friday to offer details on what was allegedly inaccurate or misleading.

SemGroup filed for Chapter 11 bankruptcy protection July 22 in Delaware, listing

Kivisto was placed on administrative leave last summer and later terminated.